Apparatus and method for supporting heterogeneous communication in wireless power transmission system

ABSTRACT

An apparatus and a method for performing handover between heterogeneous communication methods. A wireless power transmission apparatus and reception apparatus can indicate whether to support out-band communication thereof on the basis of an out-band flag. The wireless power transmission apparatus can request the wireless power reception apparatus to start a handover by using a bit pattern requesting the handover. The handover procedure to out-band may be performed in a negotiation phase or may be performed in a separate handover phase. Information for establishing an out-band communication connection can be transmitted from the wireless power reception apparatus to the wireless power transmission apparatus through in-band communication. Also, even after the handover to the out-band is completed, it is possible to periodically or intermittently perform the in-band communication in a power transmission phase to detect a swap of the wireless power reception apparatus.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.16/988,367, filed on Aug. 7, 2020, which is a continuation is pursuantto 35 U.S.C. § 119(e) of International Application No.PCT/KR2019/001819, with an international filing date of Feb. 14, 2019,which claims the benefit of U.S. Provisional Patent Application Nos.62/630,749 filed on Feb. 14, 2018, 62/631,947 filed on Feb. 19, 2018,62/633,084 filed on Feb. 21, 2018 and Korean Patent Application No.10-2018-0033061 filed on Mar. 22, 2018, the contents of which are herebyincorporated by reference herein in their entirety.

TECHNICAL FIELD

The embodiment relates to wireless charging, and more particularly, toan apparatus and method supporting heterogeneous communication in awireless power transmission system.

BACKGROUND

The wireless power transfer (or transmission) technology corresponds toa technology that can wirelessly transfer (or transmit) power between apower source and an electronic device. For example, by allowing thebattery of a wireless device, such as a smartphone or a tablet PC, andso on, to be recharged by simply loading the wireless device on awireless charging pad, the wireless power transfer technique may providemore outstanding mobility, convenience, and safety as compared to theconventional wired charging environment, which uses a wired chargingconnector. Apart from the wireless charging of wireless devices, thewireless power transfer technique is raising attention as a replacementfor the conventional wired power transfer environment in diverse fields,such as electric vehicles, Bluetooth earphones, 3D glasses, diversewearable devices, household (or home) electric appliances, furniture,underground facilities, buildings, medical equipment, robots, leisure,and so on.

The wireless power transfer (or transmission) method is also referred toas a contactless power transfer method, or a no point of contact powertransfer method, or a wireless charging method. A wireless powertransmission system may be configured of a wireless power transmittersupplying electric energy by using a wireless power transfer method, anda wireless power receiver receiving the electric energy being suppliedby the wireless power transmitter and supplying the receiving electricenergy to a receiver, such as a battery cell, and so on.

The wireless power transfer technique includes diverse methods, such asa method of transferring power by using magnetic coupling, a method oftransferring power by using radio frequency (RF), a method oftransferring power by using microwaves, and a method of transferringpower by using ultrasound (or ultrasonic waves). The method that isbased on magnetic coupling is categorized as a magnetic induction methodand a magnetic resonance method. The magnetic induction methodcorresponds to a method transmitting power by using electric currentsthat are induced to the coil of the receiver by a magnetic field, whichis generated from a coil battery cell of the transmitter, in accordancewith an electromagnetic coupling between a transmitting coil and areceiving coil. The magnetic resonance method is similar to the magneticinduction method in that is uses a magnetic field. However, the magneticresonance method is different from the magnetic induction method in thatenergy is transmitted due to a concentration of magnetic fields on botha transmitting end and a receiving end, which is caused by the generatedresonance.

In the conventional wireless power transmission system, communicationbetween a wireless power transmitter and receiver generally uses anamplitude shift keying (ASK) using a magnetic field change and frequencyshift keying (FSK) using a frequency change. However, since the ASK andthe FSK have a transfer rate of only a few kHz and are vulnerable toelectrical and magnetic disturbances, the conventional communicationscheme is not suitable for medium power level transmission required inan evolved wireless power transmission system or massive datatransmission such as authentication. Therefore, a method for selectingvarious communication protocols between the wireless power transmitterand receiver is required to support various applications of wirelesspower transmission.

SUMMARY

An aspect of the disclosure provides an apparatus and method supportingheterogeneous communication in a wireless power transmission system.

Another aspect of the disclosure provides an apparatus and methodsupporting a heterogeneous communication channel for WPC PC0 and PC1.

Still another aspect of the disclosure provides an apparatus and methodfor performing a handover between heterogeneous communication schemes ina wireless power transmission system.

Still another aspect of the disclosure provides a packet structure andprocedure for supporting a heterogeneous communication scheme in awireless power communication system.

According to an aspect of the disclosure, there is provided a wirelesspower receiver supporting heterogeneous communication. The wirelesspower receiver includes a power pick-up unit configured to receivewireless power from a wireless power transmitter through magneticcoupling with the wireless power transmitter at an operating frequencyand change an alternating current (AC) signal generated by the wirelesspower into a direct current (DC) signal, a communication/control unitconfigured to receive the DC signal provided from the power pick-up unitand perform communication with the wireless power transmitter, a loadconfigured to receive the DC signal provided from the power pick-upunit.

Herein, the communication/control unit may be configured to perform atleast one of in-band communication using the operating frequency andout-band communication using a frequency other than the operatingfrequency. The communication/control unit may be configured to receive acapability packet including an out-band flag informing whether thewireless power transmitter supports the out-band communication throughthe in-band communication in an identification and configuration phase.The communication/control unit may be configured to perform a procedurefor performing a handover to out-band, before entering a power transferphase that the power pick-up unit receives the wireless power.

In addition, the procedure of performing the handover to out-may includetransmitting information regarding the handover to out-band by thecommunication/control unit to the wireless power transmitter in anegotiation phase, based on the in-band communication.

In addition, the procedure for performing the handover to out-band mayinclude transmitting information regarding the handover to out-band bythe communication/control unit to the wireless power transmitter in ahandover phase, based on the in-band communication.

In addition, the information regarding the handover to out-band mayinclude an out-band medium access control (MAC) address packet of thewireless power receiver.

In addition, the procedure for performing the handover to out-band maybe initiated by the communication/control unit receiving a requestsignal which requests for initiation of the handover to out-band fromthe wireless power transmitter.

In addition, the request signal may be a bit pattern of 8 bits informingthe handover to out-band.

In addition, the communication/control unit may be configured to performthe out-band communication with the wireless power transmitter in thepower transfer phase based on completion of the handover procedure, andtransmit unique information or bit pattern information for swapdetection of the wireless power receiver to the wireless powertransmitter by using the in-band communication in the power transferphase.

According to another aspect of the present disclosure, there is provideda wireless power transmitter supporting heterogeneous communication. Thewireless power transmitter includes a power conversion unit configuredto transmit wireless power to a wireless power receiver through magneticcoupling with the wireless power receiver at an operating frequency, anda communication/control unit configured to perform at least one ofin-band communication using the operating frequency and out-bandcommunication using a frequency other than the operating frequency. Thecommunication/control unit may be configured to transmit a capabilitypacket including an out-band flag informing whether the wireless powertransmitter supports out-band communication to the wireless powerreceiver through the in-band communication in an identification andconfiguration phase. The communication/control unit may be configured toperform a procedure for performing a handover to out-band, beforeentering a power transfer phase that the power pick-up unit transmitsthe wireless power.

In addition, the procedure for performing the handover to out-band mayinclude receiving information regarding the handover to out-band by thecommunication/control unit to the wireless power receiver in anegotiation phase, based on the in-band communication.

In addition, the procedure for performing the handover to out-band mayinclude receiving information regarding the handover to out-band by thecommunication/control unit to the wireless power receiver in a handoverphase, based on the in-band communication.

In addition, the information regarding the handover to out-band mayinclude an out-band MAC address packet of the wireless power receiver.

In addition, the procedure for performing the handover to out-band maybe initiated by the communication/control unit transmitting a requestsignal which requests for initiation of the handover to out-band fromthe wireless power receiver.

In addition, the request signal may be a bit pattern of 8 bits informingthe handover to out-band.

In addition, the communication/control unit may be configured to performthe out-band communication with the wireless power receiver in the powertransfer phase based on completion of the handover procedure, andreceive unique information or bit pattern information for swap detectionof the wireless power receiver from the wireless power receiver by usingthe in-band communication in the power transfer phase.

According to another aspect of the present disclosure, there is provideda method of performing heterogeneous communication by a wireless powerreceiver configured to receive wireless power from a wireless powertransmitter through magnetic coupling with the wireless powertransmitter at an operating frequency. The method includes receiving acapability packet including an out-band flag informing whether thewireless power transmitter supports out-band communication using afrequency other than the operating frequency from the wireless powertransmitter through in-band communication using the operating frequencyin an identification and configuration phase, receiving a request signalwhich requests for a handover to out-band from the wireless powertransmitter, performing the handover to out-band, receiving the wirelesspower in a power transfer phase, and transmitting identificationinformation for swap detection of the wireless power receiver to thewireless power transmitter by using the in-band communication in thepower transfer phase.

Since various communication protocols can be selected depending on apower class between a wireless power transmitter and receiver, variousapplications of wireless power transmission can be supported.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a wireless power system (10) according toan embodiment.

FIG. 2 is a block diagram of a wireless power system (10) according toanother embodiment.

FIG. 3 shows an exemplary embodiment of diverse electronic devicesadopting a wireless power transmission system.

FIG. 4 is a block diagram of a wireless power transmission systemaccording to another embodiment.

FIG. 5 is a state transition diagram for describing a wireless powertransfer procedure.

FIG. 6 shows a power control method according to an embodiment.

FIG. 7 is a block diagram of a wireless power transmitter according toanother embodiment.

FIG. 8 shows a wireless power receiver according to another embodiment.

FIG. 9 shows a communication frame structure according to an embodiment.

FIG. 10 is a structure of a sync pattern according to an embodiment.

FIG. 11 shows operation statuses of a wireless power transmitter and awireless power receiver in a shared mode according to an embodiment.

FIG. 12 shows a structure of a capability packet of a wireless powertransmitter according to an embodiment.

FIG. 13 shows a structure of a configuration packet of a wireless powerreceiver according to an embodiment.

FIG. 14 is a drawing illustrating a bit pattern used in a handoverrequest to out-band according to an embodiment.

FIG. 15 is a state diagram illustrating a procedure of performing ahandover to out-band according to an embodiment.

FIG. 16 is a state diagram illustrating a procedure in which a handoverto out-band is performed according to another embodiment.

FIG. 17 is a flowchart illustrating a procedure of performing a handoverto out-band in a negotiation phase according to an embodiment.

FIG. 18 shows out-band link information according to an embodiment.

FIG. 19 is a state diagram illustrating a procedure of performing ahandover to out-band according to another embodiment.

FIG. 20 is an operational flowchart of a wireless power receiversupporting out-band communication in an identification and configurationphase according to FIG. 19.

FIG. 21 is an operational flowchart of a wireless power transmittersupporting out-band communication in an identification and configurationphase according to FIG. 19.

FIG. 22 is a diagram in which subsequent phases based on a responsesignal of a wireless power transmitter are classified in terms of apower class in an identification and configuration phase of FIG. 19.

FIG. 23 is a flowchart illustrating a procedure of performing a handoverto out-band in a handover phase according to an embodiment.

FIG. 24 is a flowchart of performing a handover to out-band in anegotiation phase according to another embodiment.

FIG. 25 is an operational flowchart of a wireless power transmitter andreceiver in a calibration phase according to an embodiment.

FIG. 26 is an operational flowchart of a wireless power transmitter andreceiver in a power transfer phase according to an embodiment.

FIG. 27 is a flowchart illustrating a procedure of performing a handoverto Bluetooth and a simulation of a required time according to anembodiment.

FIG. 28 is a flowchart illustrating an advertising operation timing inBluetooth communication.

FIG. 29 shows an example of an ADV_IND packet.

FIG. 30 is a flowchart illustrating a transmitting timing of aCONNECTION_IND message in Bluetooth communication.

FIG. 31 shows an example of a structure of a CONNECT_IND message.

FIG. 32 is a flowchart illustrating a timing of a link connection setupin Bluetooth communication.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

The term “wireless power”, which will hereinafter be used in thisspecification, will be used to refer to an arbitrary form of energy thatis related to an electric field, a magnetic field, and anelectromagnetic field, which is transferred (or transmitted) from awireless power transmitter to a wireless power receiver without usingany physical electromagnetic conductors. The wireless power may also bereferred to as a wireless power signal, and this may refer to anoscillating magnetic flux that is enclosed by a primary coil and asecondary coil. For example, power conversion for wirelessly chargingdevices including mobile phones, cordless phones, iPods, MP3 players,headsets, and so on, within the system will be described in thisspecification. Generally, the basic principle of the wireless powertransfer technique includes, for example, all of a method oftransferring power by using magnetic coupling, a method of transferringpower by using radio frequency (RF), a method of transferring power byusing microwaves, and a method of transferring power by using ultrasound(or ultrasonic waves).

FIG. 1 is a block diagram of a wireless power system (10) according toan embodiment.

Referring to FIG. 1, the wireless power system (10) include a wirelesspower transmitter (100) and a wireless power receiver (200).

The wireless power transmitter (100) is supplied with power from anexternal power source (S) and generates a magnetic field. The wirelesspower receiver (200) generates electric currents by using the generatedmagnetic field, thereby being capable of wirelessly receiving power.

Additionally, in the wireless power system (10), the wireless powertransmitter (100) and the wireless power receiver (200) may transceive(transmit and/or receive) diverse information that is required for thewireless power transfer. Herein, communication between the wirelesspower transmitter (100) and the wireless power receiver (200) may beperformed (or established) in accordance with any one of an in-bandcommunication, which uses a magnetic field that is used for the wirelesspower transfer (or transmission), and an out-band communication, whichuses a separate communication carrier.

Herein, the wireless power transmitter (100) may be provided as a fixedtype or a mobile (or portable) type. Examples of the fixed transmittertype may include an embedded type, which is embedded in in-door ceilingsor wall surfaces or embedded in furniture, such as tables, an implantedtype, which is installed in out-door parking lots, bus stops, subwaystations, and so on, or being installed in means of transportation, suchas vehicles or trains. The mobile (or portable) type wireless powertransmitter (100) may be implemented as a part of another device, suchas a mobile device having a portable size or weight or a cover of alaptop computer, and so on.

Additionally, the wireless power receiver (200) should be interpreted asa comprehensive concept including diverse home appliances and devicesthat are operated by being wirelessly supplied with power instead ofdiverse electronic devices being equipped with a battery and a powercable. Typical examples of the wireless power receiver (200) may includeportable terminals, cellular phones, smartphones, personal digitalassistants (PDAs), portable media players (PDPs), Wibro terminals,tablet PCs, phablet, laptop computers, digital cameras, navigationterminals, television, electronic vehicles (EVs), and so on.

In the wireless power system (10), one wireless power receiver (200) ora plurality of wireless power receivers may exist. Although it is shownin FIG. 1 that the wireless power transmitter (100) and the wirelesspower receiver (200) send and receive power to and from one another in aone-to-one correspondence (or relationship), as shown in FIG. 2, it isalso possible for one wireless power transmitter (100) to simultaneouslytransfer power to multiple wireless power receivers (200-1, 200-2, . . ., 200-M). Most particularly, in case the wireless power transfer (ortransmission) is performed by using a magnetic resonance method, onewireless power transmitter (100) may transfer power to multiple wirelesspower receivers (200-1, 200-2, . . . , 200-M) by using a synchronizedtransport (or transfer) method or a time-division transport (ortransfer) method.

Additionally, although it is shown in FIG. 1 that the wireless powertransmitter (100) directly transfers (or transmits) power to thewireless power receiver (200), the wireless power system (10) may alsobe equipped with a separate wireless power transceiver, such as a relayor repeater, for increasing a wireless power transport distance betweenthe wireless power transmitter (100) and the wireless power receiver(200). In this case, power is delivered to the wireless powertransceiver from the wireless power transmitter (100), and, then, thewireless power transceiver may transfer the received power to thewireless power receiver (200).

Hereinafter, the terms wireless power receiver, power receiver, andreceiver, which are mentioned in this specification, will refer to thewireless power receiver (200). Also, the terms wireless powertransmitter, power transmitter, and transmitter, which are mentioned inthis specification, will refer to the wireless power transmitter (100).

FIG. 3 shows an exemplary embodiment of diverse electronic devicesadopting a wireless power transmission system.

As shown in FIG. 3, the electronic devices included in the wirelesspower transmission system are sorted in accordance with the amount oftransmitted power and the amount of received power. Referring to FIG. 3,wearable devices, such as smart watches, smart glasses, head mounteddisplays (HMDs), smart rings, and so on, and mobile electronic devices(or portable electronic devices), such as earphones, remote controllers,smartphones, PDAs, tablet PCs, and so on, may adopt a low-power(approximately 5 W or less or approximately 20 W or less) wirelesscharging method.

Small-sized/Mid-sized electronic devices, such as laptop computers,robot vacuum cleaners, TV receivers, audio devices, vacuum cleaners,monitors, and so on, may adopt a mid-power (approximately 50 W or lessor approximately 200 W or less) wireless charging method. Kitchenappliances, such as mixers, microwave ovens, electric rice cookers, andso on, and personal transportation devices (or other electric devices ormeans of transportation), such as powered wheelchairs, powered kickscooters, powered bicycles, electric cars, and so on may adopt ahigh-power (approximately 2 kW or less or approximately 22 kW or less)wireless charging method.

The electric devices or means of transportation, which are describedabove (or shown in FIG. 1) may each include a wireless power receiver,which will hereinafter be described in detail. Therefore, theabove-described electric devices or means of transportation may becharged (or re-charged) by wirelessly receiving power from a wirelesspower transmitter.

Hereinafter, although the this specification will be described based ona mobile device adopting the wireless power charging method, this ismerely exemplary. And, therefore, it shall be understood that thewireless charging method according to this specification may be appliedto diverse electronic devices.

Wireless power transmitters and receivers may provide a very convenientuser experience and interface (UX/UI). That is, a smart wirelesscharging service may be provided, and the smart wireless chargingservice may be implemented based on a UX/UI of a smartphone including awireless power transmitter. For these applications, an interface betweena processor of a smartphone and a wireless charging receiver allows for“drop and play” two-way communication between the wireless powertransmitter and the wireless power receiver.

As an example, a user may experience a smart wireless charging servicein a hotel. When the user enters a hotel room and puts a smartphone on awireless charger in the room, the wireless charger transmits wirelesspower to the smartphone and the smartphone receives wireless power. Inthis process, the wireless charger transmits information on the smartwireless charging service to the smartphone. When it is detected thatthe smartphone is located on the wireless charger, when it is detectedthat wireless power is received, or when the smartphone receivesinformation on the smart wireless charging service from the wirelesscharger, the smartphone enters a state of inquiring the user aboutagreement (opt-in) of supplemental features. To this end, the smartphonemay display a message on a screen in a manner with or without an alarmsound. An example of the message may include the phrase “Welcome to ###hotel. Select “Yes” to activate smart charging functions: Yes|NoThanks.” The smartphone receives an input from the user who selects Yesor No Thanks, and performs a next procedure selected by the user. If Yesis selected, the smartphone transmits corresponding information to thewireless charger. The smartphone and the wireless charger perform thesmart charging function together.

The smart wireless charging service may also include receiving WiFicredentials auto-filled. For example, the wireless charger transmits theWiFi credentials to the smartphone, and the smartphone automaticallyinputs the WiFi credentials received from the wireless charger byrunning an appropriate application.

The smart wireless charging service may also include running a hotelapplication that provides hotel promotions or obtaining remotecheck-in/check-out and contact information.

As another example, the user may experience the smart wireless chargingservice in a vehicle. When the user gets in the vehicle and puts thesmartphone on the wireless charger, the wireless charger transmitswireless power to the smartphone and the smartphone receives wirelesspower. In this process, the wireless charger transmits information onthe smart wireless charging service to the smartphone. When it isdetected that the smartphone is located on the wireless charger, whenwireless power is detected to be received, or when the smartphonereceives information on the smart wireless charging service from thewireless charger, the smartphone enters a state of inquiring the userabout checking identity.

In this state, the smartphone is automatically connected to the vehiclevia WiFi and/or Bluetooth. The smartphone may display a message on thescreen in a manner with or without an alarm sound. An example of themessage may include a phrase of “Welcome to your car. Select “Yes” tosynch device with in-car controls: Yes|No Thanks.” Upon receiving theuser's input to select Yes or No Thanks, the smartphone performs a nextprocedure selected by the user. If Yes is selected, the smartphonetransmits corresponding information to the wireless charger. Inaddition, the smartphone and the wireless charger may run an in-vehiclesmart control function together by driving in-vehicleapplication/display software. The user may enjoy the desired music andcheck a regular map location. The in-vehicle applications/displaysoftware may include an ability to provide synchronous access forpassers-by.

As another example, the user may experience smart wireless charging athome. When the user enters the room and puts the smartphone on thewireless charger in the room, the wireless charger transmits wirelesspower to the smartphone and the smartphone receives wireless power. Inthis process, the wireless charger transmits information on the smartwireless charging service to the smartphone. When it is detected thatthe smartphone is located on the wireless charger, when wireless poweris detected to be received, or when the smartphone receives informationon the smart wireless charging service from the wireless charger, thesmartphone enters a state of inquiring the user about agreement (opt-in)of supplemental features. To this end, the smartphone may display amessage on the screen in a manner with or without an alarm sound. Anexample of the message may include a phrase such as “Hi xxx, Would youlike to activate night mode and secure the building?: Yes|No Thanks.”The smartphone receives a user input to select Yes or No Thanks andperforms a next procedure selected by the user. If Yes is selected, thesmartphone transmits corresponding information to the wireless charger.The smartphones and the wireless charger may recognize at least user'spattern and recommend the user to lock doors and windows, turn offlights, or set an alarm.

A standard for the wireless power transfer (or transmission) includes awireless power consortium (WPC), an air fuel alliance (AFA), and a powermatters alliance (PMA).

The WPC standard defines a baseline power profile (BPP) and an extendedpower profile (EPP). The BPP is related to a wireless power transmitterand a wireless power receiver supporting a power transfer of 5 W, andthe EPP is related to a wireless power transmitter and a wireless powerreceiver supporting the transfer of a power range greater than 5 W andless than 30 W.

Diverse wireless power transmitters and wireless power receivers eachusing a different power level may be covered by each standard and may besorted by different power classes or categories.

For example, the WPC may categorize (or sort) the wireless powertransmitters and the wireless power receivers as PC-1, PC0, PC1, andPC2, and the WPC may provide a standard document (or specification) foreach power class (PC). The PC-1 standard relates to wireless powertransmitters and receivers providing a guaranteed power of less than 5W. The application of PC-1 includes wearable devices, such as smartwatches.

The PC0 standard relates to wireless power transmitters and receiversproviding a guaranteed power of 5 W. The PC0 standard includes an EPPhaving a guaranteed power ranges that extends to 30 W. Although in-band(IB) communication corresponds to a mandatory communication protocol ofPC0, out-of-band (OBB) communication that is used as an optional backupchannel may also be used for PC0. The wireless power receiver may beidentified by setting up an OOB flag, which indicates whether or not theOOB is supported, within a configuration packet. A wireless powertransmitter supporting the OOB may enter an OOB handover phase bytransmitting a bit-pattern for an OOB handover as a response to theconfiguration packet. The response to the configuration packet maycorrespond to an NAK, an ND, or an 8-bit pattern that is newly defined.The application of the PC0 includes smartphones.

The PC1 standard relates to wireless power transmitters and receiversproviding a guaranteed power ranging from 30 W to 150 W. OOB correspondsto a mandatory communication channel for PC1, and IB is used forinitialization and link establishment to OOB. The wireless powertransmitter may enter an OOB handover phase by transmitting abit-pattern for an OOB handover as a response to the configurationpacket. The application of the PC1 includes laptop computers or powertools.

The PC2 standard relates to wireless power transmitters and receiversproviding a guaranteed power ranging from 200 W to 2 kW, and itsapplication includes kitchen appliances.

As described above, the PCs may be differentiated in accordance with therespective power levels. And, information on whether or not thecompatibility between the same PCs is supported may be optional ormandatory. Herein, the compatibility between the same PCs indicates thatpower transmission/reception between the same PCs is possible. Forexample, in case a wireless power transmitter corresponding to PC x iscapable of performing charging of a wireless power receiver having thesame PC x, it may be understood that compatibility is maintained betweenthe same PCs. Similarly, compatibility between different PCs may also besupported. Herein, the compatibility between different PCs indicatesthat power transmission/reception between different PCs is alsopossible. For example, in case a wireless power transmittercorresponding to PC x is capable of performing charging of a wirelesspower receiver having PC y, it may be understood that compatibility ismaintained between the different PCs.

The support of compatibility between PCs corresponds to an extremelyimportant issue in the aspect of user experience and establishment ofinfrastructure. Herein, however, diverse problems, which will bedescribed below, exist in maintaining the compatibility between PCs.

In case of the compatibility between the same PCs, for example, in caseof a wireless power receiver using a lap-top charging method, whereinstable charging is possible only when power is continuously transferred,even if its respective wireless power transmitter has the same PC, itmay be difficult for the corresponding wireless power receiver to stablyreceive power from a wireless power transmitter of the power toolmethod, which transfers power non-continuously. Additionally, in case ofthe compatibility between different PCs, for example, in case a wirelesspower transmitter having a minimum guaranteed power of 200 W transferspower to a wireless power receiver having a maximum guaranteed power of5 W, the corresponding wireless power receiver may be damaged due to anovervoltage. As a result, it may be inappropriate (or difficult) to usethe PS as an index/reference standard representing/indicating thecompatibility.

Hereinafter, ‘profiles’ will be newly defined based on indexes/referencestandards representing/indicating the compatibility. More specifically,it may be understood that by maintaining compatibility between wirelesspower transmitters and receivers having the same ‘profile’, stable powertransmission/reception may be performed, and that powertransmission/reception between wireless power transmitters and receivershaving different ‘profiles’ cannot be performed. The ‘profiles’ may bedefined in accordance with whether or not compatibility is possibleand/or the application regardless of (or independent from) the powerclass.

For example, the profile may be sorted into 3 different categories, suchas i) Mobile, ii) Power tool and iii) Kitchen.

For another example, the profile may be sorted into 4 differentcategories, such as i) Mobile, ii) Power tool, iii) Kitchen, and iv)Wearable.

In case of the ‘Mobile’ profile, the PC may be defined as PC0 and/orPC1, the communication protocol/method may be defined as D3 and OOBcommunication, and the operation frequency may be defined as 87 to 205kHz, and smartphones, laptop computers, and so on, may exist as theexemplary application.

In case of the ‘Power tool’ profile, the PC may be defined as PC1, thecommunication protocol/method may be defined as D3 communication, andthe operation frequency may be defined as 87 to 145 kHz, and powertools, and so on, may exist as the exemplary application.

In case of the ‘Kitchen’ profile, the PC may be defined as PC2, thecommunication protocol/method may be defined as NFC-based communication,and the operation frequency may be defined as less than 100 kHz, andkitchen/home appliances, and so on, may exist as the exemplaryapplication.

In case of a power tool and kitchen profile, NFC communication may beused between a wireless power transmitter and receiver. The wirelesspower transmitter and receiver may exchange a WPC NFC data exchangeprofile format (NDEF) to mutually confirm that they are NFC devices. Forexample, the WPC NDEF may include an application profile field (e.g.,1B), a version field (e.g., 1B), and profile specific data (e.g., 1B).The application profile field indicates to which one of: i) mobile andcomputing; ii) a power tool; and iii) a kitchen, a corresponding devicebelongs. An upper nibble of the version field indicates a major version,and a lower nibble indicates a minor version. In addition, the profilespecific data defines content for the kitchen.

In case of the ‘Wearable’ profile, the PC may be defined as PC-1, thecommunication protocol/method may be defined as D3 communication, andthe operation frequency may be defined as 87 to 205 kHz, and wearabledevices that are worn by the users, and so on, may exist as theexemplary application.

It may be mandatory to maintain compatibility between the same profiles,and it may be optional to maintain compatibility between differentprofiles.

The above-described profiles (Mobile profile, Power tool profile,Kitchen profile, and Wearable profile) may be generalized and expressedas first to nth profile, and a new profile may be added/replaced inaccordance with the WPC standard and the exemplary embodiment.

In case the profile is defined as described above, the wireless powertransmitter may optionally perform power transmission only to thewireless power receiving corresponding to the same profile as thewireless power transmitter, thereby being capable of performing a morestable power transmission. Additionally, since the load (or burden) ofthe wireless power transmitter may be reduced and power transmission isnot attempted to a wireless power receiver for which compatibility isnot possible, the risk of damage in the wireless power receiver may bereduced.

PC1 of the ‘Mobile’ profile may be defined by being derived from anoptional extension, such as OOB, based on PC0. And, the ‘Power tool’profile may be defined as a simply modified version of the PC1 ‘Mobile’profile. Additionally, up until now, although the profiles have beendefined for the purpose of maintaining compatibility between the sameprofiles, in the future, the technology may be evolved to a level ofmaintaining compatibility between different profiles. The wireless powertransmitter or the wireless power receiver may notify (or announce) itsprofile to its counterpart by using diverse methods.

In the AFA standard, the wireless power transmitter is referred to as apower transmitting unit (PTU), and the wireless power receiver isreferred to as a power receiving unit (PRU). And, the PTU is categorizedto multiple classes, as shown in Table 1, and the PRU is categorized tomultiple classes, as shown in Table 2.

TABLE 1 Minimum value for Minimum category a maximum number P_(TX) _(—)_(IN) _(—) _(MAX) support requirement of supported devices Class 1  2 W1x Category 1 1x Category 1 Class 2 10 W 1x Category 3 2x Category 2Class 3 16 W 1x Category 4 2x Category 3 Class 4 33 W 1x Category 5 3xCategory 3 Class 5 50 W 1x Category 6 4x Category 3 Class 6 70 W 1xCategory 7 5x Category 3

TABLE 2 PRU P_(RX) _(—) _(OUT) _(—) _(MAX′) Exemplary applicationCategory 1 TBD Bluetooth headset Category 2 3.5 W Feature phone Category3 6.5 W Smartphone Category 4 13 W Tablet PC, Phablet Category 5 25 WSmall form factor laptop Category 6 37.5 W General laptop Category 7 50W Home appliance

As shown in Table 1, a maximum output power capability of Class n PTUmay be equal to or greater than the PTX_IN_MAX of the correspondingclass. The PRU cannot draw a power that is higher than the power levelspecified in the corresponding category. FIG. 4 is a block diagram of awireless power transmission system according to another embodiment.

Referring to FIG. 4, the wireless power transmission system (10)includes a mobile device (450), which wirelessly receives power, and abase station (400), which wirelessly transmits power.

As a device providing induction power or resonance power, the basestation (400) may include at least one of a wireless power transmitter(100) and a system unit (405). The wireless power transmitter (100) maytransmit induction power or resonance power and may control thetransmission. The wireless power transmitter (100) may include a powerconversion unit (110) converting electric energy to a power signal bygenerating a magnetic field through a primary coil (or primary coils),and a communications & control unit (120) controlling the communicationand power transfer between the wireless power receiver (200) in order totransfer power at an appropriate (or suitable) level. The system unit(405) may perform input power provisioning, controlling of multiplewireless power transmitters, and other operation controls of the basestation (400), such as user interface control.

The primary coil may generate an electromagnetic field by using analternating current power (or voltage or current). The primary coil issupplied with an alternating current power (or voltage or current) of aspecific frequency, which is being outputted from the power conversionunit (110). And, accordingly, the primary coil may generate a magneticfield of the specific frequency. The magnetic field may be generated ina non-radial shape or a radial shape. And, the wireless power receiver(200) receives the generated magnetic field and then generates anelectric current. In other words, the primary coil wirelessly transmitspower.

In the magnetic induction method, a primary coil and a secondary coilmay have randomly appropriate shapes. For example, the primary coil andthe secondary coil may correspond to copper wire being wound around ahigh-permeability formation, such as ferrite or a non-crystalline metal.The primary coil may also be referred to as a primary core, a primarywinding, a primary loop antenna, and so on. Meanwhile, the secondarycoil may also be referred to as a secondary core, a secondary winding, asecondary loop antenna, a pickup antenna, and so on.

In case of using the magnetic resonance method, the primary coil and thesecondary coil may each be provided in the form of a primary resonanceantenna and a secondary resonance antenna. The resonance antenna mayhave a resonance structure including a coil and a capacitor. At thispoint, the resonance frequency of the resonance antenna may bedetermined by the inductance of the coil and a capacitance of thecapacitor. Herein, the coil may be formed to have a loop shape. And, acore may be placed inside the loop. The core may include a physicalcore, such as a ferrite core, or an air core.

The energy transmission (or transfer) between the primary resonanceantenna and the second resonance antenna may be performed by a resonancephenomenon occurring in the magnetic field. When a near fieldcorresponding to a resonance frequency occurs in a resonance antenna,and in case another resonance antenna exists near the correspondingresonance antenna, the resonance phenomenon refers to a highly efficientenergy transfer occurring between the two resonance antennas that arecoupled with one another. When a magnetic field corresponding to theresonance frequency is generated between the primary resonance antennaand the secondary resonance antenna, the primary resonance antenna andthe secondary resonance antenna resonate with one another. And,accordingly, in a general case, the magnetic field is focused toward thesecond resonance antenna at a higher efficiency as compared to a casewhere the magnetic field that is generated from the primary antenna isradiated to a free space. And, therefore, energy may be transferred tothe second resonance antenna from the first resonance antenna at a highefficiency. The magnetic induction method may be implemented similarlyto the magnetic resonance method. However, in this case, the frequencyof the magnetic field is not required to be a resonance frequency.Nevertheless, in the magnetic induction method, the loops configuringthe primary coil and the secondary coil are required to match oneanother, and the distance between the loops should be very close-ranged.

Although it is not shown in the drawing, the wireless power transmitter(100) may further include a communication antenna. The communicationantenna may transmit and/or receive a communication signal by using acommunication carrier apart from the magnetic field communication. Forexample, the communication antenna may transmit and/or receivecommunication signals corresponding to Wi-Fi, Bluetooth, Bluetooth LE,ZigBee, NFC, and so on.

The communications & control unit (120) may transmit and/or receiveinformation to and from the wireless power receiver (200). Thecommunications & control unit (120) may include at least one of an D3communication module and an OOB communication module.

The IB communication module may transmit and/or receive information byusing a magnetic wave, which uses a specific frequency as its centerfrequency. For example, the communications & control unit (120) mayperform in-band (IB) communication by loading information in themagnetic wave and by transmitting the information through the primarycoil or by receiving a magnetic wave carrying information through theprimary coil. At this point, the communications & control unit (120) mayload information in the magnetic wave or may interpret the informationthat is carried by the magnetic wave by using a modulation scheme, suchas binary phase shift keying (BPSK) or amplitude shift keying (ASK), andso on, or a coding scheme, such as Manchester coding ornon-return-to-zero level (NZR-L) coding, and so on. By using theabove-described IB communication, the communications & control unit(120) may transmit and/or receive information to distances of up toseveral meters at a data transmission rate of several kbps.

The OOB communication module may also perform out-of-band communicationthrough a communication antenna. For example, the communications &control unit (120) may be provided to a near field communication module.Examples of the near field communication module may includecommunication modules, such as Wi-Fi, Bluetooth, Bluetooth LE, ZigBee,NFC, and so on.

The communications & control unit (120) may control the overalloperations of the wireless power transmitter (100). The communications &control unit (120) may perform calculation and processing of diverseinformation and may also control each configuration element of thewireless power transmitter (100).

The communications & control unit (120) may be implemented in a computeror a similar device as hardware, software, or a combination of the same.When implemented in the form of hardware, the communications & controlunit (120) may be provided as an electronic circuit performing controlfunctions by processing electrical signals. And, when implemented in theform of software, the communications & control unit (120) may beprovided as a program that operates the communications & control unit(120).

By controlling the operation point, the communications & control unit(120) may control the transmitted power. The operation point that isbeing controlled may correspond to a combination of a frequency (orphase), a duty cycle, a duty ratio, and a voltage amplitude. Thecommunications & control unit (120) may control the transmitted power byadjusting any one of the frequency (or phase), the duty cycle, the dutyratio, and the voltage amplitude. Additionally, the wireless powertransmitter (100) may supply a consistent level of power, and thewireless power receiver (200) may control the level of received power bycontrolling the resonance frequency.

The mobile device (450) includes a wireless power receiver (200)receiving wireless power through a secondary coil, and a load (455)receiving and storing the power that is received by the wireless powerreceiver (200) and supplying the received power to the device.

The wireless power receiver (200) may include a power pick-up unit (210)and a communications & control unit (220). The power pick-up unit (210)may receive wireless power through the secondary coil and may convertthe received wireless power to electric energy. The power pick-up unit(210) rectifies the alternating current (AC) signal, which is receivedthrough the secondary coil, and converts the rectified signal to adirect current (DC) signal. The communications & control unit (220) maycontrol the transmission and reception of the wireless power (transferand reception of power).

The secondary coil may receive wireless power that is being transmittedfrom the wireless power transmitter (100). The secondary coil mayreceive power by using the magnetic field that is generated in theprimary coil. Herein, in case the specific frequency corresponds aresonance frequency, magnetic resonance may occur between the primarycoil and the secondary coil, thereby allowing power to be transferredwith greater efficiency.

Although it is not shown in FIG. 4, the communications & control unit(220) may further include a communication antenna. The communicationantenna may transmit and/or receive a communication signal by using acommunication carrier apart from the magnetic field communication. Forexample, the communication antenna may transmit and/or receivecommunication signals corresponding to Wi-Fi, Bluetooth, Bluetooth LE,ZigBee, NFC, and so on.

The communications & control unit (220) may transmit and/or receiveinformation to and from the wireless power transmitter (100). Thecommunications & control unit (220) may include at least one of an D3communication module and an OOB communication module.

The IB communication module may transmit and/or receive information byusing a magnetic wave, which uses a specific frequency as its centerfrequency. For example, the communications & control unit (220) mayperform D3 communication by loading information in the magnetic wave andby transmitting the information through the secondary coil or byreceiving a magnetic wave carrying information through the secondarycoil. At this point, the communications & control unit (120) may loadinformation in the magnetic wave or may interpret the information thatis carried by the magnetic wave by using a modulation scheme, such asbinary phase shift keying (BPSK) or amplitude shift keying (ASK), and soon, or a coding scheme, such as Manchester coding or non-return-to-zerolevel (NZR-L) coding, and so on. By using the above-described IBcommunication, the communications & control unit (220) may transmitand/or receive information to distances of up to several meters at adata transmission rate of several kbps.

The OOB communication module may also perform out-of-band communicationthrough a communication antenna. For example, the communications &control unit (220) may be provided to a near field communication module.

Examples of the near field communication module may includecommunication modules, such as Wi-Fi, Bluetooth, Bluetooth LE, ZigBee,NFC, and so on.

The communications & control unit (220) may control the overalloperations of the wireless power receiver (200). The communications &control unit (220) may perform calculation and processing of diverseinformation and may also control each configuration element of thewireless power receiver (200).

The communications & control unit (220) may be implemented in a computeror a similar device as hardware, software, or a combination of the same.When implemented in the form of hardware, the communications & controlunit (220) may be provided as an electronic circuit performing controlfunctions by processing electrical signals. And, when implemented in theform of software, the communications & control unit (220) may beprovided as a program that operates the communications & control unit(220).

The load (455) may correspond to a battery. The battery may store energyby using the power that is being outputted from the power pick-up unit(210). Meanwhile, the battery is not mandatorily required to be includedin the mobile device (450). For example, the battery may be provided asa detachable external feature. As another example, the wireless powerreceiver may include an operating means that can execute diversefunctions of the electronic device instead of the battery.

As shown in the drawing, although the mobile device (450) is illustratedto be included in the wireless power receiver (200) and the base station(400) is illustrated to be included in the wireless power transmitter(100), in a broader meaning, the wireless power receiver (200) may beidentified (or regarded) as the mobile device (450), and the wirelesspower transmitter (100) may be identified (or regarded) as the basestation (400).

Hereinafter, the coil or coil unit includes a coil and at least onedevice being approximate to the coil, and the coil or coil unit may alsobe referred to as a coil assembly, a coil cell, or a cell.

FIG. 5 is a state transition diagram for describing a wireless powertransfer procedure.

Referring to FIG. 5, the power transmission (or transfer) from thewireless power transmitter to the wireless power receiver according toan embodiment may be broadly divided into a selection phase (510), aping phase (520), an identification and configuration phase (530), anegotiation phase (540), a calibration phase (550), a power transferphase (560), and a renegotiation phase (570).

If a specific error or a specific event is detected when the powertransfer is initiated or while maintaining the power transfer, theselection phase (510) may include a shifting phase (or step)-referencenumerals S502, S504, S508, S510, and S512. Herein, the specific error orspecific event will be specified in the following description.Additionally, during the selection phase (510), the wireless powertransmitter may monitor whether or not an object exists on an interfacesurface. If the wireless power transmitter detects that an object isplaced on the interface surface, the process step may be shifted to theping phase (520). During the selection phase (510), the wireless powertransmitter may transmit an analog ping having an extremely short pulseand may detect whether or not an object exists within an active area ofthe interface surface based on a current change in the transmitting coilor the primary coil.

In case an object is sensed (or detected) in the selection phase (510),the wireless power transmitter may measure a quality factor of awireless power resonance circuit (e.g., power transmission coil and/orresonance capacitor). According to the embodiment, during the selectionphase (510), the wireless power transmitter may measure the qualityfactor in order to determine whether or not a foreign object exists inthe charging area along with the wireless power receiver. In the coilthat is provided in the wireless power transmitter, inductance and/orcomponents of the series resistance may be reduced due to a change inthe environment, and, due to such decrease, a value of the qualityfactor may also be decreased. In order to determine the presence orabsence of a foreign object by using the measured quality factor value,the wireless power transmitter may receive from the wireless powerreceiver a reference quality factor value, which is measured in advancein a state where no foreign object is placed within the charging area.The wireless power transmitter may determine the presence or absence ofa foreign object by comparing the measured quality factor value with thereference quality factor value, which is received during the negotiationphase (540). However, in case of a wireless power receiver having a lowreference quality factor value—e.g., depending upon its type, purpose,characteristics, and so on, the wireless power receiver may have a lowreference quality factor value-in case a foreign object exists, sincethe difference between the reference quality factor value and themeasured quality factor value is small (or insignificant), a problem mayoccur in that the presence of the foreign object cannot be easilydetermined. Accordingly, in this case, other determination factorsshould be further considered, or the present or absence of a foreignobject should be determined by using another method.

According to another embodiment, in case an object is sensed (ordetected) in the selection phase (510), in order to determine whether ornot a foreign object exists in the charging area along with the wirelesspower receiver, the wireless power transmitter may measure the qualityfactor value within a specific frequency area (e.g., operation frequencyarea). In the coil that is provided in the wireless power transmitter,inductance and/or components of the series resistance may be reduced dueto a change in the environment, and, due to such decrease, the resonancefrequency of the coil of the wireless power transmitter may be changed(or shifted). More specifically, a quality factor peak frequency thatcorresponds to a frequency in which a maximum quality factor value ismeasured within the operation frequency band may be moved (or shifted).

In the ping phase (520), if the wireless power transmitter detects thepresence of an object, the transmitter activates (or Wakes up) areceiver and transmits a digital ping for identifying whether or not thedetected object corresponds to the wireless power receiver. During theping phase (520), if the wireless power transmitter fails to receive aresponse signal for the digital ping—e.g., a signal intensitypacket—from the receiver, the process may be shifted back to theselection phase (510). Additionally, in the ping phase (520), if thewireless power transmitter receives a signal indicating the completionof the power transfer—e.g., charging complete packet—from the receiver,the process may be shifted back to the selection phase (510).

If the ping phase (520) is completed, the wireless power transmitter mayshift to the identification and configuration phase (530) foridentifying the receiver and for collecting configuration and statusinformation.

In the identification and configuration phase (530), if the wirelesspower transmitter receives an unwanted packet (i.e., unexpected packet),or if the wireless power transmitter fails to receive a packet during apredetermined period of time (i.e., out of time), or if a packettransmission error occurs (i.e., transmission error), or if a powertransfer contract is not configured (i.e., no power transfer contract),the wireless power transmitter may shift to the selection phase (510).

The wireless power transmitter may confirm (or verify) whether or notits entry to the negotiation phase (540) is needed based on aNegotiation field value of the configuration packet, which is receivedduring the identification and configuration phase (530). Based on theverified result, in case a negotiation is needed, the wireless powertransmitter enters the negotiation phase (540) and may then perform apredetermined FOD detection procedure. Conversely, in case a negotiationis not needed, the wireless power transmitter may immediately enter thepower transfer phase (560).

In the negotiation phase (540), the wireless power transmitter mayreceive a Foreign Object Detection (FOD) status packet that includes areference quality factor value. Or, the wireless power transmitter mayreceive an FOD status packet that includes a reference peak frequencyvalue. Alternatively, the wireless power transmitter may receive astatus packet that includes a reference quality factor value and areference peak frequency value. At this point, the wireless powertransmitter may determine a quality coefficient threshold value for FOdetection based on the reference quality factor value. The wirelesspower transmitter may determine a peak frequency threshold value for FOdetection based on the reference peak frequency value.

The wireless power transmitter may detect the presence or absence of anFO in the charging area by using the determined quality coefficientthreshold value for FO detection and the currently measured qualityfactor value (i.e., the quality factor value that was measured beforethe ping phase), and, then, the wireless power transmitter may controlthe transmitted power in accordance with the FO detection result. Forexample, in case the FO is detected, the power transfer may be stopped.However, this specification will not be limited only to this.

The wireless power transmitter may detect the presence or absence of anFO in the charging area by using the determined peak frequency thresholdvalue for FO detection and the currently measured peak frequency value(i.e., the peak frequency value that was measured before the pingphase), and, then, the wireless power transmitter may control thetransmitted power in accordance with the FO detection result. Forexample, in case the FO is detected, the power transfer may be stopped.However, this specification will not be limited only to this.

In case the FO is detected, the wireless power transmitter may return tothe selection phase (510). Conversely, in case the FO is not detected,the wireless power transmitter may proceed to the calibration phase(550) and may, then, enter the power transfer phase (560). Morespecifically, in case the FO is not detected, the wireless powertransmitter may determine the intensity of the received power that isreceived by the receiving end during the calibration phase (550) and maymeasure power loss in the receiving end and the transmitting end inorder to determine the intensity of the power that is transmitted fromthe transmitting end. In other words, during the calibration phase(550), the wireless power transmitter may estimate the power loss basedon a difference between the transmitted power of the transmitting endand the received power of the receiving end. The wireless powertransmitter according to the embodiment may calibrate the thresholdvalue for the FOD detection by applying the estimated power loss.

In the power transfer phase (560), in case the wireless powertransmitter receives an unwanted packet (i.e., unexpected packet), or incase the wireless power transmitter fails to receive a packet during apredetermined period of time (i.e., time-out), or in case a violation ofa predetermined power transfer contract occurs (i.e., power transfercontract violation), or in case charging is completed, the wirelesspower transmitter may shift to the selection phase (510).

Additionally, in the power transfer phase (560), in case the wirelesspower transmitter is required to reconfigure the power transfer contractin accordance with a status change in the wireless power transmitter,the wireless power transmitter may shift to the renegotiation phase(570). At this point, if the renegotiation is successfully completed,the wireless power transmitter may return to the power transfer phase(560).

The above-described power transfer contract may be configured based onthe status and characteristic information of the wireless powertransmitter and receiver. For example, the wireless power transmitterstatus information may include information on a maximum amount oftransmittable power, information on a maximum number of receivers thatcan be accommodated, and so on. And, the receiver status information mayinclude information on the required power, and so on.

FIG. 6 shows a power control method according to an embodiment.

As shown in FIG. 6, in the power transfer phase (560), by alternatingthe power transmission and/or reception and communication, the wirelesspower transmitter (100) and the wireless power receiver (200) maycontrol the amount (or size) of the power that is being transferred. Thewireless power transmitter and the wireless power receiver operate at aspecific control point. The control point indicates a combination of thevoltage and the electric current that are provided from the output ofthe wireless power receiver, when the power transfer is performed.

More specifically, the wireless power receiver selects a desired controlpoint, a desired output current/voltage, a temperature at a specificlocation of the mobile device, and so on, and additionally determines anactual control point at which the receiver is currently operating. Thewireless power receiver calculates a control error value by using thedesired control point and the actual control point, and, then, thewireless power receiver may transmit the calculated control error valueto the wireless power transmitter as a control error packet.

Also, the wireless power transmitter may configure/control a newoperation point-amplitude, frequency, and duty cycle-by using thereceived control error packet, so as to control the power transfer.Therefore, the control error packet may be transmitted/received at aconstant time interval during the power transfer phase, and, accordingto the exemplary embodiment, in case the wireless power receiverattempts to reduce the electric current of the wireless powertransmitter, the wireless power receiver may transmit the control errorpacket by setting the control error value to a negative number. And, incase the wireless power receiver intends to increase the electriccurrent of the wireless power transmitter, the wireless power receivertransmit the control error packet by setting the control error value toa positive number. During the induction mode, by transmitting thecontrol error packet to the wireless power transmitter as describedabove, the wireless power receiver may control the power transfer.

In the resonance mode, which will hereinafter be described in detail,the device may be operated by using a method that is different from theinduction mode. In the resonance mode, one wireless power transmittershould be capable of serving a plurality of wireless power receivers atthe same time. However, in case of controlling the power transfer justas in the induction mode, since the power that is being transferred iscontrolled by a communication that is established with one wirelesspower receiver, it may be difficult to control the power transfer ofadditional wireless power receivers. Therefore, in the resonance modeaccording to this specification, a method of controlling the amount ofpower that is being received by having the wireless power transmittercommonly transfer (or transmit) the basic power and by having thewireless power receiver control its own resonance frequency.Nevertheless, even during the operation of the resonance mode, themethod described above in FIG. 6 will not be completely excluded. And,additional control of the transmitted power may be performed by usingthe method of FIG. 6.

FIG. 7 is a block diagram of a wireless power transmitter according toanother embodiment. This may belong to a wireless power transmissionsystem that is being operated in the magnetic resonance mode or theshared mode. The shared mode may refer to a mode performing aseveral-for-one (or one-to-many) communication and charging between thewireless power transmitter and the wireless power receiver. The sharedmode may be implemented as a magnetic induction method or a resonancemethod.

Referring to FIG. 7, the wireless power transmitter (700) may include atleast one of a cover (720) covering a coil assembly, a power adapter(730) supplying power to the power transmitter (740), a powertransmitter (740) transmitting wireless power, and a user interface(750) providing information related to power transfer processing andother related information. Most particularly, the user interface (750)may be optionally included or may be included as another user interface(750) of the wireless power transmitter (700).

The power transmitter (740) may include at least one of a coil assembly(760), an impedance matching circuit (770), an inverter (780), acommunication unit (790), and a control unit (710).

The coil assembly (760) includes at least one primary coil generating amagnetic field. And, the coil assembly (760) may also be referred to asa coil cell.

The impedance matching circuit (770) may provide impedance matchingbetween the inverter and the primary coil(s). The impedance matchingcircuit (770) may generate resonance from a suitable frequency thatboosts the electric current of the primary coil(s). In a multi-coilpower transmitter (740), the impedance matching circuit may additionallyinclude a multiplex that routes signals from the inverter to a subset ofthe primary coils. The impedance matching circuit may also be referredto as a tank circuit.

The impedance matching circuit (770) may include a capacitor, aninductor, and a switching device that switches the connection betweenthe capacitor and the inductor. The impedance matching may be performedby detecting a reflective wave of the wireless power that is beingtransferred (or transmitted) through the coil assembly (760) and byswitching the switching device based on the detected reflective wave,thereby adjusting the connection status of the capacitor or the inductoror adjusting the capacitance of the capacitor or adjusting theinductance of the inductor. In some cases, the impedance matching may becarried out even though the impedance matching circuit (770) is omitted.This specification also includes an exemplary embodiment of the wirelesspower transmitter (700), wherein the impedance matching circuit (770) isomitted.

The inverter (780) may convert a DC input to an AC signal. The inverter(780) may be operated as a half-bridge inverter or a full-bridgeinverter in order to generate a pulse wave and a duty cycle of anadjustable frequency. Additionally, the inverter may include a pluralityof stages in order to adjust input voltage levels.

The communication unit (790) may perform communication with the powerreceiver. The power receiver performs load modulation in order tocommunicate requests and information corresponding to the powertransmitter. Therefore, the power transmitter (740) may use thecommunication unit (790) so as to monitor the amplitude and/or phase ofthe electric current and/or voltage of the primary coil in order todemodulate the data being transmitted from the power receiver.

Additionally, the power transmitter (740) may control the output powerto that the data can be transferred through the communication unit (790)by using a Frequency Shift Keying (FSK) method, and so on.

The control unit (710) may control communication and power transfer (ordelivery) of the power transmitter (740). The control unit (710) maycontrol the power transfer by adjusting the above-described operationpoint. The operation point may be determined by, for example, at leastany one of the operation frequency, the duty cycle, and the inputvoltage.

The communication unit (790) and the control unit (710) may each beprovided as a separate unit/device/chipset or may be collectivelyprovided as one unit/device/chipset.

FIG. 8 shows a wireless power receiver according to another embodiment.This may belong to a wireless power transmission system that is beingoperated in the magnetic resonance mode or the shared mode.

Referring to FIG. 8, the wireless power receiver (800) may include atleast one of a user interface (820) providing information related topower transfer processing and other related information, a powerreceiver (830) receiving wireless power, a load circuit (840), and abase (850) supporting and covering the coil assembly. Most particularly,the user interface (820) may be optionally included or may be includedas another user interface (820) of the wireless power receiver (800).

The power receiver (830) may include at least one of a power converter(860), an impedance matching circuit (870), a coil assembly (880), acommunication unit (890), and a control unit (810).

The power converter (860) may convert the AC power that is received fromthe secondary coil to a voltage and electric current that are suitablefor the load circuit. According to an exemplary embodiment, the powerconverter (860) may include a rectifier. The rectifier may rectify thereceived wireless power and may convert the power from an alternatingcurrent (AC) to a direct current (DC). The rectifier may convert thealternating current to the direct current by using a diode or atransistor, and, then, the rectifier may smooth the converted current byusing the capacitor and resistance. Herein, a full-wave rectifier, ahalf-wave rectifier, a voltage multiplier, and so on, that areimplemented as a bridge circuit may be used as the rectifier.Additionally, the power converter may adapt a reflected impedance of thepower receiver.

The impedance matching circuit (870) may provide impedance matchingbetween a combination of the power converter (860) and the load circuit(840) and the secondary coil. According to an exemplary embodiment, theimpedance matching circuit may generate a resonance of approximately 100kHz, which can reinforce the power transfer. The impedance matchingcircuit (870) may include a capacitor, an inductor, and a switchingdevice that switches the combination of the capacitor and the inductor.The impedance matching may be performed by controlling the switchingdevice of the circuit that configured the impedance matching circuit(870) based on the voltage value, electric current value, power value,frequency value, and so on, of the wireless power that is beingreceived. In some cases, the impedance matching may be carried out eventhough the impedance matching circuit (870) is omitted. Thisspecification also includes an exemplary embodiment of the wirelesspower receiver (200), wherein the impedance matching circuit (870) isomitted.

The coil assembly (880) includes at least one secondary coil, and,optionally, the coil assembly (880) may further include an elementshielding the metallic part of the receiver from the magnetic field.

The communication unit (890) may perform load modulation in order tocommunicate requests and other information to the power transmitter.

For this, the power receiver (830) may perform switching of theresistance or capacitor so as to change the reflected impedance.

The control unit (810) may control the received power. For this, thecontrol unit (810) may determine/calculate a difference between anactual operation point and a desired operation point of the powerreceiver (830). Thereafter, by performing a request for adjusting thereflected impedance of the power transmitter and/or for adjusting anoperation point of the power transmitter, the difference between theactual operation point and the desired operation point may beadjusted/reduced. In case of minimizing this difference, an optimalpower reception may be performed.

The communication unit (890) and the control unit (810) may each beprovided as a separate device/chipset or may be collectively provided asone device/chipset.

FIG. 9 shows a communication frame structure according to an embodiment.This may correspond to a communication frame structure in a shared mode.

Referring to FIG. 9, in the shared mode, different forms of frames maybe used along with one another. For example, in the shared mode, aslotted frame having a plurality of slots, as shown in (A), and a freeformat frame that does not have a specified format, as shown in (B), maybe used. More specifically, the slotted frame corresponds to a frame fortransmitting short data packets from the wireless power receiver (200)to the wireless power transmitter (100). And, since the free formatframe is not configured of a plurality of slots, the free format framemay correspond to a frame that is capable of performing transmission oflong data packets.

Meanwhile, the slotted frame and the free format frame may be referredto other diverse terms by anyone skilled in the art. For example, theslotted frame may be alternatively referred to as a channel frame, andthe free format frame may be alternatively referred to as a messageframe.

More specifically, the slotted frame may include a sync patternindicating the starting point (or beginning) of a slot, a measurementslot, nine slots, and additional sync patterns each having the same timeinterval that precedes each of the nine slots.

Herein, the additional sync pattern corresponds to a sync pattern thatis different from the sync pattern that indicates the starting point ofthe above-described frame. More specifically, the additional syncpattern does not indicate the starting point of the frame but mayindicate information related to the neighboring (or adjacent) slots(i.e., two consecutive slots positioned on both sides of the syncpattern).

Among the nine slots, each sync pattern may be positioned between twoconsecutive slots. In this case, the sync pattern may provideinformation related to the two consecutive slots.

Additionally, the nine slots and the sync patterns being provided beforeeach of the nine slots may have the same time interval. For example, thenine slots may have a time interval of 50 ms. And, the nine syncpatterns may have a time length of 50 ms.

Meanwhile, the free format frame, as shown in (B) may not have aspecific format apart from the sync pattern indicating the startingpoint of the frame and the measurement slot. More specifically, the freeformat frame is configured to perform a function that is different fromthat of the slotted frame. For example, the free format frame may beused to perform a function of performing communication of long datapackets (e.g., additional owner information packets) between thewireless power transmitter and the wireless power receiver, or, in caseof a wireless power transmitter being configured of multiple coils, toperform a function of selecting any one of the coils.

Hereinafter, a sync pattern that is included in each frame will bedescribed in more detail with reference to the accompanying drawings.

FIG. 10 is a structure of a sync pattern according to an embodiment.

Referring to FIG. 10, the sync pattern may be configured of a preamble,a start bit, a response field, a type field, an info field, and a paritybit. In FIG. 10, the start bit is illustrated as ZERO.

More specifically, the preamble is configured of consecutive bits, andall of the bits may be set to 0. In other words, the preamble maycorrespond to bits for matching a time length of the sync pattern.

The number of bits configuring the preamble may be subordinate to theoperation frequency so that the length of the sync pattern can be mostapproximate to 50 ms but within a range that does not exceed 50 ms. Forexample, in case the operation frequency corresponds to 100 kHz, thesync pattern may be configured of two preamble bits, and, in case theoperation frequency corresponds to 105 kHz, the sync pattern may beconfigured of three preamble bits.

The start bit may correspond to a bit that follows the preamble, and thestart bit may indicate ZERO. The ZERO may correspond to a bit thatindicates a type of the sync pattern. Herein, the type of sync patternsmay include a frame sync including information that is related to aframe, and a slot sync including information of the slot. Morespecifically, the sync pattern may be positioned between consecutiveframes and may correspond to a frame sync that indicate a start of theframe, or the sync pattern may be positioned between consecutive slotsamong a plurality of slots configuring the frame and may correspond to async slot including information related to the consecutive slots.

For example, in case the ZERO is equal to 0, this may indicate that thecorresponding slot is a slot sync that is positioned in-between slots.And, in case the ZERO is equal to 1, this may indicate that thecorresponding sync pattern is a frame sync being located in-betweenframes.

A parity bit corresponds to a last bit of the sync pattern, and theparity bit may indicate information on a number of bits configuring thedata fields (i.e., the response field, the type field, and the infofield) that are included in the sync pattern. For example, in case thenumber of bits configuring the data fields of the sync patterncorresponds to an even number, the parity bit may be set to when, and,otherwise (i.e., in case the number of bits corresponds to an oddnumber), the parity bit may be set to 0.

The response field may include response information of the wirelesspower transmitter for its communication with the wireless power receiverwithin a slot prior to the sync pattern. For example, in case acommunication between the wireless power transmitter and the wirelesspower receiver is not detected, the response field may have a value of‘00’. Additionally, if a communication error is detected in thecommunication between the wireless power transmitter and the wirelesspower receiver, the response field may have a value of ‘01’. Thecommunication error corresponds to a case where two or more wirelesspower receivers attempt to access one slot, thereby causing collision tooccur between the two or more wireless power receivers.

Additionally, the response field may include information indicatingwhether or not the data packet has been accurately received from thewireless power receiver. More specifically, in case the wireless powertransmitter has denied the data packet, the response field may have avalue of “10” (10—not acknowledge (NAK)). And, in case the wirelesspower transmitter has confirmed the data packet, the response field mayhave a value of “11” (11—acknowledge (ACK)).

The type field may indicate the type of the sync pattern. Morespecifically, in case the sync pattern corresponds to a first syncpattern of the frame (i.e., as the first sync pattern, in case the syncpattern is positioned before the measurement slot), the type field mayhave a value of ‘1’, which indicates a frame sync.

Additionally, in a slotted frame, in case the sync pattern does notcorrespond to the first sync pattern of the frame, the type field mayhave a value of ‘0’, which indicates a slot sync.

Moreover, the information field may determine the meaning of its valuein accordance with the sync pattern type, which is indicated in the typefield. For example, in case the type field is equal to 1 (i.e., in casethe sync pattern type indicates a frame sync), the meaning of theinformation field may indicate the frame type. More specifically, theinformation field may indicate whether the current frame corresponds toa slotted frame or a free-format frame. For example, in case theinformation field is given a value of ‘00’, this indicates that thecurrent frame corresponds to a slotted frame. And, in case theinformation field is given a value of ‘01’, this indicates that thecurrent frame corresponds to a free-format frame.

Conversely, in case the type field is equal to 0 (i.e., in case the syncpattern type indicates a slot sync), the information field may indicatea state of a next slot, which is positioned after the sync pattern. Morespecifically, in case the next slot corresponds to a slot that isallocated (or assigned) to a specific wireless power receiver, theinformation field is given a value of ‘00’. In case the next slotcorresponds to a slot that is locked, so as to be temporarily used bythe specific wireless power receiver, the information field is given avalue of ‘01’. Alternatively, in case the next slot corresponds to aslot that can be freely used by a random wireless power receiver, theinformation field is given a value of ‘10’.

FIG. 11 shows operation statuses of a wireless power transmitter and awireless power receiver in a shared mode according to an embodiment.

Referring to FIG. 11, the wireless power receiver operating in theshared mode may be operated in any one of a selection phase (1100), anintroduction phase (1110), a configuration phase (1120), a negotiationphase (1130), and a power transfer phase (1140).

Firstly, the wireless power transmitter according to the embodiment maytransmit a wireless power signal in order to detect the wireless powerreceiver. More specifically, a process of detecting a wireless powerreceiver by using the wireless power signal may be referred to as anAnalog ping.

Meanwhile, the wireless power receiver that has received the wirelesspower signal may enter the selection phase (1100). As described above,the wireless power receiver that has entered the selection phase (1100)may detect the presence or absence of an FSK signal within the wirelesspower signal.

In other words, the wireless power receiver may perform communication byusing any one of an exclusive mode and a shared mode in accordance withthe presence or absence of the FSK signal.

More specifically, in case the FSK signal is included in the wirelesspower signal, the wireless power receiver may operate in the sharedmode, and, otherwise, the wireless power receiver may operate in theexclusive mode.

In case the wireless power receiver operates in the shared mode, thewireless power receiver may enter the introduction phase (1110). In theintroduction phase (1110), the wireless power receiver may transmit acontrol information (CI) packet to the wireless power transmitter inorder to transmit the control information packet during theconfiguration phase, the negotiation phase, and the power transferphase. The control information packet may have a header and informationrelated to control. For example, in the control information packet, theheader may correspond to 0X53.

In the introduction phase (1110), the wireless power receiver performsan attempt to request a free slot for transmitting the controlinformation (CI) packet during the following configuration phase,negotiation phase, and power transfer phase. At this point, the wirelesspower receiver selects a free slot and transmits an initial CI packet.If the wireless power transmitter transmits an ACK as a response to thecorresponding CI packet, the wireless power transmitter enters theconfiguration phase. If the wireless power transmitter transmits a NACKas a response to the corresponding CI packet, this indicates thatanother wireless power receiver is performing communication through theconfiguration and negotiation phase. In this case, the wireless powerreceiver re-attempts to perform a request for a free slot.

If the wireless power receiver receives an ACK as a response to the CIpacket, the wireless power receiver may determine the position of aprivate slot within the frame by counting the remaining sync slots up tothe initial frame sync. In all of the subsequent slot-based frames, thewireless power receiver transmits the CI packet through thecorresponding slot.

If the wireless power transmitter authorizes the entry of the wirelesspower receiver to the configuration phase, the wireless powertransmitter provides a locked slot series for the exclusive usage of thewireless power receiver. This may ensure the wireless power receiver toproceed to the configuration phase without any collision.

The wireless power receiver transmits sequences of data packets, such astwo identification data packets (IDHI and IDLO), by using the lockedslots. When this phase is completed, the wireless power receiver entersthe negotiation phase. During the negotiation state, the wireless powertransmitter continues to provide the locked slots for the exclusiveusage of the wireless power receiver. This may ensure the wireless powerreceiver to proceed to the negotiation phase without any collision.

The wireless power receiver transmits one or more negotiation datapackets by using the corresponding locked slot, and the transmittednegotiation data packet(s) may be mixed with the private data packets.Eventually, the corresponding sequence is ended (or completed) alongwith a specific request (SRQ) packet. When the corresponding sequence iscompleted, the wireless power receiver enters the power transfer phase,and the wireless power transmitter stops the provision of the lockedslots.

In the power transfer phase, the wireless power receiver performs thetransmission of a CI packet by using the allocated slots and thenreceives the power. The wireless power receiver may include a regulatorcircuit. The regulator circuit may be included in acommunication/control unit. The wireless power receiver mayself-regulate a reflected impedance of the wireless power receiverthrough the regulator circuit. In other words, the wireless powerreceiver may adjust the impedance that is being reflected for an amountof power that is requested by an external load. This may prevent anexcessive reception of power and overheating.

In the shared mode, (depending upon the operation mode) since thewireless power transmitter may not perform the adjustment of power as aresponse to the received CI packet, in this case, control may be neededin order to prevent an overvoltage state.

In the wireless power transmission system, communication between awireless power transmitter and receiver generally uses an amplitudeshift keying (ASK) using a magnetic field change and frequency shiftkeying (FSK) using a frequency change. However, since the ASK and theFSK have a transfer rate of only a few kHz and are vulnerable toelectrical and magnetic disturbances, the ASK or the FSK is not suitablefor medium power level transmission required in an evolved wirelesspower transmission system or massive data transmission such asauthentication. Therefore, a method for selecting various communicationprotocols between the wireless power transmitter and receiver isrequired to support various applications of wireless power transmission.In the present specification, out-band communication differs fromout-of-band (OOB) communication only in terms of expression and issubstantially the same term. Therefore, it will be collectivelydescribed hereinafter as out-band communication.

Hereinafter, a switching operation between in-band communication andout-band communication is called a handover. In particular, an operationin which a wireless power transmitter and receiver switch from thein-band communication to the out-band communication is called a handoverto out-band, and an operation in which the wireless power transmitterand receiver switch from the out-band communication to the in-bandcommunication is called a handover to in-band. The out-bandcommunication may include, for example, Bluetooth or Bluetooth lowenergy (BLE) or NFC.

In order to enable the handover to out-band, both the wireless powertransmitter and receiver shall not only support the out-bandcommunication but also know whether the out-band communication ispossible in the other party. Whether the wireless power transmitter andreceiver support the out-band communication may be checked by acorresponding power class and information on whether the out-bandcommunication is supported. In addition, if the handover to out-band ispossible, a procedure or packet for determining (or selecting) andinitiating the handover to out-band shall be defined. Hereinafter,information, packet, and procedure related to the handover to out-bandwill be disclosed.

Information and Packet Related to Handover to Out-Band

In an aspect, whether a wireless power transmitter supports out-bandcommunication may be determined by a capability packet. The capabilitypacket is a packet which is transmitted by the wireless powertransmitter during a negotiation phase in response to a general requestof a wireless power receiver. The capability packet may include powerclass information and a flag indicating whether the out-bandcommunication is supported. In addition, whether the out-bandcommunication is selected may be indicated by the flag of the capabilitypacket.

FIG. 12 shows a structure of a capability packet of a wireless powertransmitter according to an embodiment.

Referring to FIG. 12, the capability packet may be indicated by a headervalue of 0x31, and may include a power class bit/field (e.g., 2 bits), aguaranteed power value bit/field (e.g., 6 bits), a potential power valuebit/field (e.g., 6 bits), an out-band (OOB) flag field (e.g., 1 bit), awireless power identifier (WPID) bit/field (e.g., 1 bit), and/or a NotRes Sens. bit/field (e.g., 1 bit).

The power class bit/field indicates PC of a power transmitting unit.

The guaranteed power value bit/field indicates a maximum guaranteedpower value included in a power transfer contract (PTC-GP) that may benegotiated by the power transmitting unit in a current surroundingcondition. Herein, the surrounding condition may correspond to, forexample, a temperature of the power transmitting unit, an amount ofpower that may be drained by the power transmitting unit from a powersource shared with other power transmitting units, and/or the presenceor absence of a foreign object or friendly metal.

The OOB flag field is a field indicating whether the wireless powertransmitter supports out-band communication, and for example, mayindicate that the wireless power transmitter supports the out-bandcommunication if a value thereof is ‘1’b, and may indicate that thewireless power transmitter does not support out-band communication ifthe value thereof is ‘0’b.

The WPID bit/field indicates that the power transmitting unit has noability to receive a WPID packet. The Not Res Sens. bit/field may be setto a different value for each design of an individual power transmittingunit. In general, this bit/field may be set to a value ‘0’ to indicate adesign of a power transmitting unit capable of frequency control of lessthan 150 kHz with a power transfer contract including a maximum powervalue greater than 5 W.

During the negotiation phase, the wireless power receiver may receiveand read the capability packet of the wireless power transmitter toidentify whether the wireless power transmitter supports out-bandcommunication. When the out-band communication is selected by thecapability packet during the negotiation phase, a handover to out-bandmay be performed.

In another aspect, whether the wireless power receiver supports out-bandcommunication may be determined by a configuration packet. Herein, theconfiguration packet is information generated by the wireless powerreceiver and transmitted to the wireless power transmitter, and mayinclude an out-band flag (or OOB flag) indicating whether the wirelesspower receiver supports the out-band communication. The wireless powerreceiver may set the out-band flag in the configuration packet toindicate that the wireless power receiver supports the out-bandcommunication.

FIG. 13 shows a structure of a configuration packet of a wireless powerreceiver according to an embodiment.

Referring to FIG. 13, the configuration packet may be indicated by aheader value of 0x51, and may include a power class bit/field (e.g., 2bits), a maximum power value bit/field (e.g., 6 bits), an out-band flagfield (e.g., 1 bit), a prop bit/field (e.g., 1 bit), a count bit/field(e.g., 3 bit)s, a window size bit/field (e.g., 5 bits), a window offsetbit/field (e.g., 5 bits), a window offset bit/field (e.g., 3 bits), aNeg bit/field (e.g., 1 bit), a polarity bit/field (e.g., 1 bit), and/ora depth bit/field (e.g., 2 bits).

The power class bit/field indicates PC of a power receiving unit.

The maximum power value bit/field may indicate different informationaccording to whether the power receiving unit supports a foreign objectdetection (FOD) (extension) function. If the power receiving unit doesnot support the FOD extension function, this bit/field may indicate amaximum power amount which is expected to be provided to the powerreceiving unit from a power transmitting unit/rectifier. If the powerreceiving unit supports the FOD extension function, this bit/field mayindicate a scaling factor of a received power value reported by thepower receiving unit by using a received power packet. In this case, thepower receiving unit may set this bit/field to a value twice the maximumpower amount (watt) expected to be provided.

The out-band flag field is a field indicating whether the wireless powerreceiver supports or does not support out-band communication, and forexample, may indicate that the wireless power receiver supports theout-band communication if a value thereof is ‘1’b, and may indicate thatthe wireless power receiver does not support the out-band communicationif the value thereof is ‘0’b.

The prop bit/field may indicate a power transfer control scheme of thepower transmitting unit, which is desired by the power receiving unit.

If the Neg bit/field is set to ‘0’, this may indicate that no responseis transmitted by the power transmitting unit. If this bit/field is setto ‘1’, this may indicate that the power transmitting unit has totransmit an Acknowledge (ACK) response to the power receiving unit aftera configuration packet indicating entering a negotiation phase.

If the polarity bit/field is set to ‘0’, this may indicate that thepower transmitting unit uses a default FSK polarity. If this bit/fieldis set to ‘1’, this may indicate that the power transmitting unit uses arevered FSK polarity.

The depth bit/field may indicate a depth of FSK modulation.

The count bit/field may indicate the number of optional configurationpackets transmitted by the power receiving unit in theidentification/configuration phase.

The window size bit/field may indicate an averaged window size ofreceived power in unit of 4 ms.

The window offset bit/field may indicate a time interval between awindow for averaging received power and received power packettransmission in unit of 4 ms.

In another aspect, a handover to out-band may be requested or initiatedby a bit-pattern for OOB handover.

FIG. 14 is a drawing illustrating a bit pattern used in a handoverrequest to out-band according to an embodiment.

Referring to FIG. 14, upon confirming that a wireless power receiversupports out-band communication, a wireless power transmitter mayrequest for a handover to out-band by transmitting a specific bitpattern (e.g., 8 bits as shown in FIG. 14) to the wireless powerreceiver in response thereto. Herein, the bit pattern may re-utilize theexisting NAK(00000000) or ND(10101010), and may be a newly defined value(e.g., 00110011) as a response for a configuration packet of thewireless power receiver.

The wireless power transmitter according to the embodiment of FIG. 12 toFIG. 14 corresponds to the wireless power transmitter, wireless powertransmitting unit, or power transmitting portion of FIG. 1 to FIG. 11.Therefore, an operation of the wireless power transmitter in the presentembodiment is implemented by combining one or two or more of componentsof the wireless power transmitter of FIG. 1 to FIG. 11. For example, inthe present embodiment, an operation of generating and transmitting acapability packet, an operation of selecting out-band communication andperforming a handover, an operation of generating and transmitting a bitpattern for handover, an operation of requesting for a handover toout-band, an operation of receiving a configuration packet, or the likemay be performed by the communication/control unit 120.

In addition, the wireless power receiver according to the embodiment ofFIG. 12 to FIG. 14 corresponds to the wireless power receiver, wirelesspower receiving unit, or power receiving portion of FIG. 1 to FIG. 11.Therefore, an operation of the wireless power receiver in the presentembodiment is implemented by combining one or two or more of componentsof the wireless power receiver of FIG. 1 to FIG. 11. For example, in thepresent embodiment, an operation of checking whether the wireless powertransmitter supports out-band communication by receiving and reading acapability packet of the wireless power transmitter, an operation ofchecking whether the wireless power transmitter support the out-bandcommunication, an operation of selecting the out-band communication andperforming handover, an operation of generating and transmitting aconfiguration packet, an operation of receiving a bit pattern forhandover, or the like may be performed by the communication/control unit220.

Procedure of Handover to Out-Band

Hereinafter, a method in which a wireless power transmitter and awireless power receiver perform a procedure for performing a handover toout-band is disclosed in detail.

The wireless power transmitter and receiver may mutually exchange apacket by using a specific communication method according to a powerclass (PC) or according to a phase.

If at least one of the wireless power transmitter and receiver belongsto the PC, in-band communication may be mandatory while out-bandcommunication may be optional. That is, the out-band communication maybe used as an optional backup channel.

If the wireless power transmitter and receiver belong to PC1, both thein-band communication and the out-band communication may be mandatory.In this case, the wireless power transmitter and/or the wireless powerreceiver may perform a handover to out-band communication after startingin-band communication in an initial stage. In this case, the handover toout-band may be achieved through in-band communication. In other words,the in-band communication is used for charging initialization and linkestablishment to OOB.

In case of the PC1, since out-band communication is mandatory, the PC1wireless power transmitter may omit transmission of a packet (e.g., thecapability packet of FIG. 12) for reporting whether it supports theout-band communication. That is, upon confirming that the wireless powerreceiver supports the out-band communication, the wireless powertransmitter may request for the handover to out-band by transmitting abit pattern (e.g., a bit pattern of FIG. 14) for handover to thewireless power receiver. According to an embodiment, a capability packetmay also be transmitted in the PC1 to report whether the out-bandcommunication is supported.

Next, a communication scheme that can be supported by the wireless powertransmitter and receiver is described according to a phase.

The wireless power transmitter and receiver may mutually exchange apacket by using a specific communication method in any one a pluralityof phases as shown in FIG. 5. In this case, the communication method mayinclude at least one of in-band communication and out-bandcommunication. That is, the wireless power transmitter and receiver mayperform the in-band communication in a first phase, and may perform theout-band communication in a second phase. Herein, the first phase inwhich the wireless power transmitter and/or the wireless power receiverperform the in-band communication and the second phase in which thewireless power transmitter and/or the wireless power receiver performthe out-band communication may be defined variously. For example, thefirst phase is an initialization step of wireless charging, and mayinclude a selection phase, a ping phase, an identification &configuration phase, and a negotiation phase. The second phase is amid-late step of wireless charging, and may include a calibration phaseand a power transfer phase.

The procedure for performing the handover to out-band may be definedwithout having to add a new phase to the existing phases, and anadditional new phase may be prepared for the procedure for performing ahandover to out-band. An embodiment of the former case may include acase where the procedure for performing a handover to out-band proceedsin the negotiation phase. An embodiment of the latter case may include acase where a handover phase is defined as a new phase.

Hereinafter, a method of performing a handover to out-band by a wirelesspower transmitter and receiver will be described by comprehensivelyconsidering a power class and a phase.

Embodiment in which Handover Procedure is Performed in Negotiation Phase

According to the present embodiment, a handover decision, initiation,and out-band communication initiation and link establishment areachieved by in-band communication in a negotiation phase.

Meanwhile, whether a handover to out-band is performed may be determinedbased on the number of several cases. As described above, in PC1, sinceout-band communication is mandatory, the wireless power receiver of PC1supports the out-band communication by default. However, in PC0, theout-band communication is optional, and the wireless power transmitteror receiver may support or may not support the out-band communication.Therefore, the wireless power transmitter and receiver may have variousnumbers of cases according to a power class and according to whether theout-band communication is supported. A first case is a case where thewireless power receiver belongs to PC0 and does not support the out-bandcommunication. A second case is a case where the wireless power receiverbelongs to PC0, and supports the out-band communication. A third case isa case where the wireless power receiver belongs to PC1, and mandatorilysupports the out-band communication.

A handover procedure may be determined depending on the number ofseveral cases. Hereinafter, a procedure for performing a handover toout-band of the wireless power receiver is described by using a statediagram.

FIG. 15 is a state diagram illustrating a procedure of performing ahandover to out-band according to an embodiment. A wireless powertransmitter and wireless power receiver according to FIG. 15 may belongto PC0 or PC1.

Referring to FIG. 15, a first phase to which in-band communication isapplied includes a selection phase (S1500), a ping phase (S1510), anidentification and configuration phase (S1520), and a negotiation phase(S1530). In the negotiation phase (S1530), power contract (S1531) may beachieved.

In an aspect, if at least one of the wireless power transmitter and thewireless power receiver belongs to PC0, out-band communication may beoptional. Therefore, the selection phase (S1532) of in-bandcommunication and out-band communication may be performed in thenegotiation phase (S1530), and the out-band communication may beselected in the selection phase (S1532). If the in-band communication isselected, the wireless power transmitter and receiver exchangeparameters related to the in-band communication. For example, thein-band communication may include communication from the wireless powertransmitter to the wireless power receiver. In this case, sincecommunication is FSK, a parameter to be exchanged and related to in-bandcommunication may include an FSK parameter (S1533). Thereafter, thewireless power transmitter and receiver enter a power transfer phase(S1550) through a calibration phase (S1540), and the in-bandcommunication is used to transmit packets (e.g., packets related toauthentication and power control) during the power transfer phase.

Meanwhile, upon detecting the out-band communication in the step S1532,a second state in which the out-band communication is applied includes acalibration phase (S1560) and a power transfer phase (S1570). Thewireless power transmitter and receiver enter the power transfer phase(S1570) via the connection phase (S1560), and the out-band communicationis used to transmit packets (e.g., packets related to authentication andpower control) during the power transfer phase.

In another aspect, if both the wireless power transmitter and thewireless power receiver belong to PC1, out-band communication may bemandatory. Therefore, in case of PC1, the selection phase (S1532) may beomitted, and the handover to out-band may be achieved through in-bandcommunication. Subsequently, the calibration phase (S1560) and the powertransfer phase (S1570) may be performed identically.

When t is a time required from the selection phase (S1500) to thein-band or out-band selection phase (S1532), at least hundreds ofmilliseconds (ms) may be required for t.

The wireless power transmitter according to the embodiment of FIG. 15corresponds to the wireless power transmitter, wireless powertransmitting unit, or power transmitting portion of FIG. 1 to FIG. 11.Therefore, an operation of the wireless power transmitter in the presentembodiment is implemented by combining one or two or more of componentsof the wireless power transmitter of FIG. 1 to FIG. 11. For example, theselection phase (S1532) of in-band communication and out-bandcommunication may be performed in the negotiation phase (S1530), and anoperation of selecting out-band communication or in-band communication,an operation of exchanging parameters related to in-band communication(S1533), an operation of transmitting or receiving packets (e.g.,packets related to authentication and power control) during a powertransfer phase by using out-band communication, an operation ofdetecting a swap, or the like may be performed by thecommunication/control unit 120.

In addition, the wireless power receiver according to the presentembodiment corresponds to the wireless power receiver, wireless powerreceiving unit, or power receiving portion of FIG. 1 to FIG. 11.Therefore, an operation of the wireless power receiver in the presentembodiment is implemented by combining one or two or more of componentsof the wireless power receiver of FIG. 1 to FIG. 11. For example, theselection phase (S1532) of in-band communication and out-bandcommunication may be performed in the negotiation phase (S1530), and anoperation of selecting out-band communication or in-band communication,an operation of exchanging parameters related to in-band communication(S1533), an operation of transmitting or receiving packets (e.g.,packets related to authentication and power control) during a powertransfer phase by using out-band communication, an operation ofdetecting a swap, or the like may be performed by thecommunication/control unit 220.

FIG. 16 is a state diagram illustrating a procedure in which a handoverto out-band is performed according to another embodiment.

Referring to FIG. 16, in-band communication is used in a selection phase(S1600), a ping phase (S1605), and an identification and configurationphase (S1610). Thereafter, in a negotiation phase (S1615), according towhether a wireless power receiver supports out-band communication, thein-band communication may be continuously used or a handover to out-bandis performed.

If the wireless power receiver belongs to PC0 and does not supportout-band communication (PC0 PRx not supporting OOB), the in-bandcommunication is used continuously in the negotiation phase (S1615), acalibration phase (S1620), a power transfer phase (S1625), and are-negotiation phase (S1630).

If the wireless power receiver belongs to PC1 or supports out-bandcommunication while belonging to PC0 (PC0 PRx supporting OOB), ahandover is achieved from in-band to out-band, and the out-bandcommunication is used continuously in a negotiation phase (S1635), acalibration phase (S1640), and a power transfer phase (S1645).

A wireless power transmitter may detect a sudden impedance change (achange in the amount of current flowing in a transmission coil) duringwireless power transmission. The cause of the sudden impedance changemay include a sudden location shift of the wireless power receiver or aswap of the wireless power receiver.

In this case, in order to detect the swap by identifying the wirelesspower transmitter, the wireless power transmitter and the wireless powerreceiver may perform swap detection intermittently or periodically byusing in-band communication in the power transfer phase or by usingin-band communication at the request of the wireless power transmitter(S1650).

If the swap is detected, the wireless power transmitter and the wirelesspower receiver return to the selection phase (S1600). Herein, the swapof the wireless power receiver is a phenomenon in which another deviceother than the wireless power receiver for which wireless charging isoriginally intended is connected for out-band to the wireless powertransmitter. Due to the swap detection, the wireless power transmitterand receiver may perform out-band communication and in-bandcommunication simultaneously during the power transfer phase.

The swap detection may include an operation in which the wireless powerreceiver transmits unique information to the wireless power transmitter,based on in-band communication. That is, the swap detection may beperformed in such a manner that a currently serving wireless powerreceiver is identified to check whether it is a previously servedwireless power receiver. For example, the unique information includes anID packet. For another example, the unique information includes a randomnumber. For another example, the unique information includes BLE deviceaddress information of the wireless power receiver used in the switchingfrom in-band to out-band. For another example, the unique informationmay include at least one of the ID packet, the random number, and theBLE device address information.

Meanwhile, the swap detection may be performed periodically orintermittently by the wireless power receiver irrespective of therequest of the wireless power transmitter, or may be performed at therequest of the wireless power transmitter.

In an aspect, the swap detection at the request of the wireless powertransmitter may include a step in which the wireless power transmitteruses out-band communication to request the wireless power receiver toprovide unique information of the wireless power receiver. For example,the unique information of the wireless power receiver includes an IDpacket. For another example, the unique information of the wirelesspower receiver includes a random number. For another example the uniqueinformation of the wireless power receiver includes BLE device addressinformation of the wireless power receiver used in the switching fromin-band to out-band. For another example, the unique information mayinclude at least one of the ID packet, the random number, and the BLEdevice address information.

Herein, the step in which the wireless power transmitter requests forthe unique information of the wireless power receiver may include a stepin which the wireless power transmitter transmits its uniqueinformation. Herein, the unique information of the wireless powertransmitter may be transmitted optionally. That is, the wireless powertransmitter may transmit, or may not transmit, the unique information ofthe wireless power transmitter to the wireless power receiver. In thiscase, the wireless power receiver determines whether the uniqueinformation of the wireless power transmitter is received from thewireless power transmitter. If the wireless power transmitter does nottransmit its unique information to the wireless power receiver, thewireless power receiver transmits default unique information to thewireless power transmitter. The default unit information may include,for example, the BLE device address information.

The wireless power transmitter may determine whether the swap occursbased on the unique information of the wireless power receiver. Forexample, if the wireless power receiver transmits the unique informationof the wireless power receiver by using in-band communication and thewireless power transmitter receives the unique information of thewireless power receiver, the wireless power transmitter determines thatthe swap does not occur. Otherwise, if the wireless power receiver doesnot transmit the unique information of the wireless power receiver byusing in-band communication within a specific given time or if thewireless power transmitter fails in reception of the unique informationof the wireless power receiver despite the fact that the uniqueinformation of the wireless power receiver is transmitted, the wirelesspower transmitter may determine that the swap occurs.

In another aspect, the swap detection at the request of the wirelesspower transmitter may include a step in which the wireless powertransmitter uses out-band communication to request the wireless powerreceiver to provide bit pattern information of the wireless powerreceiver and a step in which the wireless power receiver uses in-bandcommunication (ASK) to transmit the bit pattern information to thewireless power transmitter in response to the request. The presentembodiment may further include a step in which the wireless powerreceiver changes impedance at the request of the wireless powertransmitter, and a step in which the wireless power transmitter detectsthe changed impedance to confirm that it is still in a magnetic couplingstate with respect to the same wireless power receiver (or it is placedabove the wireless power transmitter). If swapping occurs and thus thewireless power transmitter is in a magnetic coupling state with respectto another wireless power receiver (or if another wireless powerreceiver is placed above the wireless power transmitter), swapping canbe detected since the wireless power receiver does not respond to therequest of the wireless power transmitter. In this case, uniqueinformation of the wireless power transmitter or receiver is notparticularly required. Since there may be problem in quality of in-bandcommunication when high-power transmission is performed, in order toimprove swap detection performance, a method of transferring simple bitpattern information as shown in the present embodiment may be morepreferable than a packet type.

Due to the swap detection, the handover to out-band can guarantee that alink connection between the wireless power transmitter and receiver ispaired for wireless charging without any cross-reference issue.

The wireless power transmitter according to the embodiment of FIG. 16corresponds to the wireless power transmitter, wireless powertransmitting unit, or power transmitting portion of FIG. 1 to FIG. 11.Therefore, an operation of the wireless power transmitter in the presentembodiment is implemented by combining one or two or more of componentsof the wireless power transmitter of FIG. 1 to FIG. 11. For example, anoperation of performing in-band communication for charginginitialization and link establishment to OOB, an operation of requestingfor entering the OOB handover phase by transmitting a bit pattern forhandover to the wireless power receiver, an operation of performing swapdetection, or the like in the present embodiment may be performed by thecommunication/control unit 120.

In addition, the wireless power receiver according to the embodiment ofFIG. 16 corresponds to the wireless power receiver, wireless powerreceiving unit, or power receiving portion of FIG. 1 to FIG. 11.Therefore, an operation of the wireless power receiver in the presentembodiment is implemented by combining one or two or more of componentsof the wireless power receiver of FIG. 1 to FIG. 11. For example, anoperation of performing in-band communication for charginginitialization and link establishment to OOB, an operation of receivinga bit pattern for handover, an operation of performing swap detection,or the like in the present embodiment may be performed by thecommunication/control unit 220.

Which communication protocol or communication method is applied to eachphase on the entire phase diagram is described in FIG. 15 and FIG. 16,whereas which procedure is used to perform a handover to out-band in anegotiation phase will be described hereinafter.

FIG. 17 is a flowchart illustrating a procedure of performing a handoverto out-band in a negotiation phase according to an embodiment.

Referring to FIG. 17, the negotiation phase includes a communicationduration and an out-band communication duration. The in-bandcommunication duration includes steps S1700 to S1710, and the out-bandcommunication duration includes steps S1720 to S1735.

First, in the in-band communication duration, a wireless power receivertransmits a general request packet (GRQ/Cap) to a wireless powertransmitter to request for a capability packet (S1700). The wirelesspower transmitter transmits the capability packet in response to thegeneral request packet (S1705). Herein, an example of the capabilitypacket is shown in FIG. 12.

When an out-band flag included in the capability packet indicates thatout-band communication is supported, the wireless power receivertransmits OOB link information to the wireless power transmitter(S1710). The OOB link information is transmitted through in-bandcommunication, and for example, may have a packet structure of FIG. 18.

FIG. 18 shows OOB link information according to an embodiment.

The OOB link information may also be called a Bluetooth (or BLE) mediumaccess control (MAC) packet of a wireless power receiver.

Referring to FIG. 18, in a negotiation phase, the wireless powerreceiver may transmit, to a wireless power transmitter, identificationinformation (e.g., Bluetooth (or BLE) MAC address (6 bytes)) capable ofuniquely identifying the wireless power receiver in out-band by usingin-band communication. In this case, the Bluetooth (or BLE) MAC addressmay be transmitted to a power transmitting unit through a newly definedpacket or the existing packet transmitted/received in the negotiationphase. However, the OOB link information is not limited thereto, and maybe defined as various packet formats indicating the Bluetooth (or BLE)MAC address of the wireless transmission receiver.

In addition, WPID may be used as identification information capable ofuniquely identifying the wireless power receiver. In this case, the WPIDmay be a BLE device address of the wireless power receiver.

Referring back to FIG. 17, upon successfully receiving a correspondingpacket without error, in response thereto, the wireless powertransmitter may transmit an acknowledgement (ACK) to the wireless powerreceiver (S1715).

If the OOB link information is successfully transmitted, the in-bandcommunication duration in the negotiation phase ends to enter theout-band communication duration. In an out-band communication duration,the wireless power transmitter and receiver may mutuallytransmit/receive packets and signals by using the out-band communicationprotocol/scheme and the MAC address related to out-band, therebyestablishing an out-band connection (or link).

To this end, the wireless power transmitter transmits to the wirelesspower receiver a CONNECT_REQ message for requesting for establishing theout-band connection with the wireless power receiver. The MAC address ofthe wireless power transmitter and parameters required to establish theout-band connection between the wireless power transmitter and receivermay be included in the CONNECT_REQ message.

If the wireless power receiver grants an out-band connection request ofthe wireless power transmitter, the wireless power receiver transmits anACK message to the wireless power transmitter in response to theCONNECT_REQ message (S1725). Accordingly, out-band connectionestablishment may be complete. A service in an out-band profile (e.g., aBluetooth profile) established in this case may be set to‘WPC_service_UUID’. The wireless power transmitter may operate by beingset to a master (link layer), a central (generic access profile (GAP)),and a client (generic attribute profile (GATT)). The wireless powerreceiver may operate by being set to a slave (link layer), a peripheral(GAP), and a server (GATT).

Next, an authentication procedure may be performed between the wirelesspower transmitter and receiver (S1730). After the authenticationprocedure is successfully complete, the wireless power transmitter andreceiver transmit/receive mutual static information and dynamicinformation by using out-band communication, and a power contract may beachieved by using the out-band communication. For example, the wirelesspower transmitter may transmit a guaranteed power (GP) and a potentialpower (PP) to the wireless power receiver, and the wireless powerreceiver may transmit max power to the wireless power transmitter.

The wireless power transmitter according to the embodiment of FIG. 17corresponds to the wireless power transmitter, wireless powertransmitting unit, or power transmitting portion of FIG. 1 to FIG. 11.Therefore, an operation of the wireless power transmitter in the presentembodiment is implemented by combining one or two or more of componentsof the wireless power transmitter of FIG. 1 to FIG. 11. For example,operations of the wireless power receiver of the steps S1700 to S1735 inthe present embodiment may be performed by the communication/controlunit 120.

In addition, the wireless power receiver according to the embodiment ofFIG. 16 corresponds to the wireless power receiver, wireless powerreceiving unit, or power receiving portion of FIG. 1 to FIG. 11.Therefore, an operation of the wireless power receiver in the presentembodiment is implemented by combining one or two or more of componentsof the wireless power receiver of FIG. 1 to FIG. 11. For example,operations of the wireless power receiver of the steps S1700 to S1735 inthe present embodiment may be performed by the communication/controlunit 220.

Embodiment in which Handover Procedure is Performed in Handover Phase

FIG. 19 is a state diagram illustrating a procedure of performing ahandover to out-band according to another embodiment. A differencebetween the embodiment of FIG. 19 and the embodiment of FIG. 16 lies ina phase in which the handover to out-band is performed. That is, thehandover is performed in a negotiation phase in the handover procedureof FIG. 16, whereas the handover to out-band is performed not in thenegotiation phase but in a separate handover phase in the handoverprocedure of FIG. 19. The handover phase is a new phase defined after anidentification and configuration phase.

Specifically, referring to FIG. 19, in-band communication is used in aselection phase (S1900), a ping phase (S1905), and an identification andconfiguration phase (S1910). After the identification and configurationphase (S1910), according to whether a wireless power receiver supportsout-band communication, in-band communication may be continuously usedor a handover to out-band is performed.

If the wireless power receiver belongs to PC0 and does not supportout-band communication (PC0 PRx not supporting OOB), in-bandcommunication is used continuously in a negotiation phase (S1915), acalibration phase (S1920), a power transfer phase (S1925), and are-negotiation phase (S1930).

If the wireless power receiver belongs to PC1 or supports out-bandcommunication while belonging to PC0 (PC0 PRx supporting OOB), thewireless power transmitter and receiver enter a handover phase (S1935)according to a handover request to out-band of the wireless powertransmitter. In the handover phase (S1935), a handover is achieved fromin-band to out-band, and the out-band communication is used continuouslyin a negotiation phase (S1940), a calibration phase (S1945), and a powertransfer phase (S1950). In this case, in order to detect the swap byidentifying the wireless power transmitter, the wireless powertransmitter and the wireless power receiver may perform swap detectionintermittently or periodically in the power transfer phase or by usingin-band communication at the request of the wireless power transmitter(S1955). For swap detection, the wireless power receiver may transmitunique information to the wireless power transmitter by using in-bandcommunication. In addition, transmission of the unique information orswap detection may be triggered at the request of the wireless powertransmitter.

In an aspect, the swap detection at the request of the wireless powertransmitter may include a step in which the wireless power transmitteruses out-band communication to request the wireless power receiver toprovide unique information of the wireless power receiver. For example,the unique information of the wireless power receiver includes an IDpacket. For another example, the unique information of the wirelesspower receiver includes a random number. For another example the uniqueinformation of the wireless power receiver includes BLE device addressinformation of the wireless power receiver used in the switching fromin-band to out-band. For another example, the unique information mayinclude at least one of the ID packet, the random number, and the BLEdevice address information.

Herein, the step in which the wireless power transmitter requests forthe unique information of the wireless power receiver may include a stepin which the wireless power transmitter transmits its uniqueinformation. Herein, the unique information of the wireless powertransmitter may be transmitted optionally. That is, the wireless powertransmitter may transmit, or may not transmit, the unique information ofthe wireless power transmitter to the wireless power receiver. In thiscase, the wireless power receiver determines whether the uniqueinformation of the wireless power transmitter is received from thewireless power transmitter. If the wireless power transmitter does nottransmit its unique information to the wireless power receiver, thewireless power receiver transmits default unique information to thewireless power transmitter. The default unit information may include,for example, the BLE device address information.

The wireless power transmitter may determine whether the swap occursbased on the unique information of the wireless power receiver. Forexample, if the wireless power receiver transmits the unique informationof the wireless power receiver by using in-band communication and thewireless power transmitter receives the unique information of thewireless power receiver, the wireless power transmitter determines thatthe swap does not occur. Otherwise, if the wireless power receiver doesnot transmit the unique information of the wireless power receiver byusing in-band communication within a specific given time or if thewireless power transmitter fails in reception of the unique informationof the wireless power receiver despite the fact that the uniqueinformation of the wireless power receiver is transmitted, the wirelesspower transmitter may determine that the swap occurs.

In another aspect, the swap detection at the request of the wirelesspower transmitter may include a step in which the wireless powertransmitter uses out-band communication to request the wireless powerreceiver to provide bit pattern information of the wireless powerreceiver and a step in which the wireless power receiver uses in-bandcommunication (ASK) to transmit the bit pattern information to thewireless power transmitter in response to the request. The presentembodiment may further include a step in which the wireless powerreceiver changes impedance at the request of the wireless powertransmitter, and a step in which the wireless power transmitter detectsthe changed impedance to confirm that it is still in a magnetic couplingstate with respect to the same wireless power receiver (or it is placedabove the wireless power transmitter). If swapping occurs and thus thewireless power transmitter is in a magnetic coupling state with respectto another wireless power receiver (or if another wireless powerreceiver is placed above the wireless power transmitter), swapping canbe detected since the wireless power receiver does not respond to therequest of the wireless power transmitter. In this case, uniqueinformation of the wireless power transmitter or receiver is notparticularly required. Since there may be problem in quality of in-bandcommunication when high-power transmission is performed, in order toimprove swap detection performance, a method of transferring simple bitpattern information as shown in the present embodiment may be morepreferable than a packet type.

If the swap is detected, the wireless power transmitter and the wirelesspower receiver return to the selection phase (S1900).

An operation of a wireless power receiver supporting out-bandcommunication in the identification and configuration phase (S1910) isdescribed in detail with reference to FIG. 20, and an operation of awireless power transmitter is described in detail with reference to FIG.21.

FIG. 20 is an operational flowchart of a wireless power receiversupporting out-band communication in an identification and configurationphase according to FIG. 19.

Referring to FIG. 20, the wireless power receiver may indicate anout-band flag to a specific value (e.g., ‘1’) to indicate that out-bandcommunication is supported (S2000). In the identification andconfiguration phase (S1910), the wireless power receiver transmits aconfiguration packet including the out-band flat to the wireless powertransmitter (S2005), and monitors a response of the wireless powertransmitter.

If the response of the wireless power transmitter is no response, thisindicates that the wireless power transmitter does not support thenegotiation phase and the out-band communication. Therefore, thewireless power receiver enters a power transfer phase (S2015). In-bandcommunication is used in the power transfer phase after phase (S2015).

If the response of the wireless power transmitter is an ACK response,this indicates that the wireless power transmitter supports thenegotiation phase but does not support out-band communication.Therefore, the wireless power receiver enters the negotiation phase ofS1915 (S2020). Since the wireless power transmitter does not supportout-band communication, in-band communication is used in phases afterthe step S2020.

If the response of the wireless power transmitters is another response(e.g., a handover request to out-band or switching to out-band) which isneither no-response nor ACK response, this indicates that the wirelesspower transmitter supports out-band communication. Therefore, thewireless power receiver enters the handover phase of S1935 (S2025).Since both the wireless power transmitter and receiver support out-bandcommunication, the out-band communication is used in phases after thestep S2025. However, for swap detection, in-band communication may beused in parallel with out-the band communication.

In addition, the wireless power receiver according to the embodiment ofFIG. 20 corresponds to the wireless power receiver, wireless powerreceiving unit, or wireless receiving portion of FIG. 1 to FIG. 11.Therefore, an operation of the wireless power receiver for each step inthe present embodiment is implemented by combining one or two or more ofcomponents of the wireless power receiver of FIG. 1 to FIG. 11. Forexample, operations based on the steps S2000 to S2025 may be performedby the communication/control unit 220.

FIG. 21 is an operational flowchart of a wireless power transmittersupporting out-band communication in an identification and configurationphase according to FIG. 19.

Referring to FIG. 21, the wireless power transmitter may check anout-band flag included in a configuration packet (S2100), and thus mayrecognize whether a wireless power receiver paired for wireless chargingsupports out-band communication. If the out-band flag is set to ‘1’,this may indicate that the wireless power receiver supports the out-bandcommunication, and if the out-band flag is set to ‘0’, this may indicatethat the wireless power receiver does not support the out-bandcommunication. If the identification result of the out-band flag showsthat the out-band flag is set to ‘1’, the wireless power transmittergenerates and transmits a response signal thereof (S2105). The responsesignal may have a specific bit pattern.

If the wireless power transmitter supports the out-band communication,the wireless power transmitter transmits a request signal for requestinga handover to out-band as a response signal to the wireless powerreceiver. Herein, the signal for requesting the handover for out-bandmay also be called another term such as a request signal for entering ahandover phase, a signal for switching to out-band, a request signal forout-band, or the like. A signal for requesting the handover to out-bandmay be a specific bit pattern. The bit pattern may reuse the existingNAK or ND, and may be a value newly defined as a response to aconfiguration packet of the wireless power receiver. The bit pattern mayconsist of 8 bits.

The wireless power transmitter enters the handover phase (S2110). Sinceboth the wireless power transmitter and receiver support the out-bandcommunication, the out-band communication is used in phases after thestep S2110. However, for swap detection, in-band communication may beused in parallel with the out-band communication.

The wireless power transmitter according to the embodiment of FIG. 21corresponds to the wireless power transmitter, wireless powertransmitting unit, or power transmitting portion of FIG. 1 to FIG. 11.Therefore, an operation of the wireless power transmitter in the presentembodiment is implemented by combining one or two or more of componentsof the wireless power transmitter of FIG. 1 to FIG. 11. For example,operations of the wireless power transmitter in the steps S2100 to S2105may be performed by the communication/control unit 120.

FIG. 22 is a diagram in which subsequent phases based on a responsesignal of a wireless power transmitter are classified in terms of apower class in an identification and configuration phase of FIG. 19.

Referring to FIG. 22, a BPP wireless power transmitter of PC0 does notsupport a negotiation phase and out-band communication. Therefore, theBPP wireless power transmitter of PC0 does not response (None) to aconfiguration packet of a wireless power receiver in an identificationand configuration phase (S2200), and the wireless power transmitter andreceiver enter a power transfer phase (S2205).

Meanwhile, an EPP wireless power transmitter of PC0 may support anegotiation phase, and may optionally support out-band communication.

If the EPP wireless power transmitter of PC0 does not support theout-band communication, the EPP wireless power transmitter of PC0transmits ACK in response to the configuration packet of the wirelesspower receiver in the identification and& configuration phase (S2200),and enters the negotiation phase (S2210).

If the wireless power transmitter belongs to PC1, or supports theout-band communication in case of not belonging to EPP of PC0, thewireless power transmitter responds to a request for OOB link (RFO) fora configuration packet of the wireless power receiver in theidentification and configuration phase (S2200), and enters the handoverphase (S2215). The RFO may be, for example, ND, NAK, or a new FSKresponse pattern of another forma. In the handover phase, when thewireless power receiver responds with ACK as a grant in response to theRFO, the wireless power transmitter and receiver enter the negotiationphase (S2220).

The wireless power transmitter according to the embodiment of FIG. 22corresponds to the wireless power transmitter, wireless powertransmitting unit, or power transmitting portion of FIG. 1 to FIG. 11.Therefore, an operation of the wireless power transmitter in the presentembodiment is implemented by combining one or two or more of componentsof the wireless power transmitter of FIG. 1 to FIG. 11. For example,operations of the wireless power transmitter in the steps S2200 to S2220may be performed by the communication/control unit 120.

In addition, the wireless power receiver according to the embodiment ofFIG. 22 corresponds to the wireless power receiver, wireless powerreceiving unit, or wireless receiving portion of FIG. 1 to FIG. 11.Therefore, an operation of the wireless power receiver for each step inthe present embodiment is implemented by combining one or two or more ofcomponents of the wireless power receiver of FIG. 1 to FIG. 11. Forexample, operations of the wireless power receiver in steps the S2200 toS2220 may be performed by the communication/control unit 220.

Which communication protocol or communication method is applied to eachphase on the entire phase diagram is described in FIG. 19 and FIG. 22,whereas which procedure is used to perform a handover to out-band in ahandover phase and a negotiation phase will be described hereinafter.

FIG. 23 is a flowchart illustrating a procedure of performing a handoverto out-band in a handover phase according to an embodiment, and FIG. 24is a flowchart of performing a handover to out-band in a negotiationphase according to another embodiment.

Comparing the embodiment based on FIG. 23 and FIG. 24 with theembodiment of FIG. 17, if the handover phase and the negotiation phaseare combined based on FIG. 23, it becomes identical to the negotiationphase based on FIG. 17. Specifically, the handover phase of FIG. 23corresponds to the in-band communication duration of FIG. 17, and thenegotiation phase of FIG. 24 corresponds to the out-band communicationduration of FIG. 17.

Therefore, an operation of the wireless power transmitter and receiverin the handover phase of FIG. 23 is identical to the operation of thewireless power transmitter and receiver in the in-band communicationduration of FIG. 17, and an operation of the wireless power transmitterand receiver in the negotiation phase of FIG. 24 is identical to theoperation of the wireless power transmitter and receiver in the out-bandcommunication duration of FIG. 17.

The wireless power transmitter according to the embodiment of FIG. 23and FIG. 24 corresponds to the wireless power transmitter, wirelesspower transmitting unit, or power transmitting portion of FIG. 1 to FIG.11. Therefore, an operation of the wireless power transmitter in thepresent embodiment is implemented by combining one or two or more ofcomponents of the wireless power transmitter of FIG. 1 to FIG. 11. Forexample, operations of the wireless power transmitter in the stepsS2200, S2305, and S2400 to S2420 may be performed by thecommunication/control unit 120.

In addition, the wireless power receiver according to the embodiment ofFIG. 23 and FIG. 24 corresponds to the wireless power receiver, wirelesspower receiving unit, or wireless receiving portion of FIG. 1 to FIG.11. Therefore, an operation of the wireless power receiver for each stepin the present embodiment is implemented by combining one or two or moreof components of the wireless power receiver of FIG. 1 to FIG. 11. Forexample, operations of the wireless power receiver in the steps S2300,S2305, and S2400 to S2420 may be performed by the communication/controlunit 220.

Embodiment of Operation after OOB Connection Establishment is Complete

Hereinafter, a detailed operation for each phase is disclosed, which isperformed after an OOB connection establishment is complete (e.g., aftera handover to out-band is complete) across a handover phase and anegotiation phase.

FIG. 25 is an operational flowchart of a wireless power transmitter andreceiver in a calibration phase according to an embodiment. Thecalibration phase of FIG. 25 may be identical to the calibration phaseof steps S1540 and S1560 of FIG. 15, the calibration phase of stepsS1620 and S2640 of FIG. 16, and the calibration phase of steps S1920 andS1945 of FIG. 19.

Referring to FIG. 25, the wireless power receiver transmits to thewireless power transmitter a received power packet (RPP) in a statewhere a load is connected to the wireless power receiver (S2500).

Next, the wireless power transmitter transmits to the wireless powerreceiver a Write_Load_ON message to inform the wireless power receiverto connect the load (S2505).

If the load is connected to the wireless power receiver in response tothe Write_Load_ON message, the wireless power receiver transmits to thewireless power transmitter the RPP in the state where the load isconnected (S2510).

FIG. 26 is an operational flowchart of a wireless power transmitter andreceiver in a power transfer phase according to an embodiment. The powertransfer phase of FIG. 26 may be identical to the power transfer phaseof steps S1550 and S1570 of FIG. 15, the power transfer phase of stepsS1625 and S1645 of FIG. 16, and the power transfer phase of steps S1925and S1950 of FIG. 19.

Referring to FIG. 26, the wireless power transmission and receivertransmit/receive mutual static information and dynamic information byusing out-band communication. For example, a control error (CE) packet,a received power packet (RPP), an end power transfer (EPT) packet, orthe like is exchanged through the out-band communication.

In this case, in order to detect a swap by identifying the wirelesspower transmitter, the wireless power transmitter and the wireless powerreceiver may perform swap detection by using in-band communicationintermittently or periodically in the power transfer phase or at therequest of the wireless power transmitter. The swap detection mayinclude an operation in which the wireless power receiver transmitsunique information (e.g., an ID packet or unique kay info) to thewireless power transmitter, based on in-band communication. That is, theswap detection may be performed in such a manner that a currentlyserving wireless power receiver is identified to check whether it is apreviously served wireless power receiver. Transmission of uniqueinformation or swap detection may be triggered at the request of thewireless power transmitter.

In an aspect, the swap detection at the request of the wireless powertransmitter may include a step in which the wireless power transmitteruses out-band communication to request the wireless power receiver toprovide unique information of the wireless power receiver. For example,the unique information of the wireless power receiver includes an IDpacket. For another example, the unique information of the wirelesspower receiver includes a random number. For another example the uniqueinformation of the wireless power receiver includes BLE device addressinformation of the wireless power receiver used in the switching fromin-band to out-band. For another example, the unique information mayinclude at least one of the ID packet, the random number, and the BLEdevice address information.

Herein, the step in which the wireless power transmitter requests forthe unique information of the wireless power receiver may include a stepin which the wireless power transmitter transmits its uniqueinformation. Herein, the unique information of the wireless powertransmitter may be transmitted optionally. That is, the wireless powertransmitter may transmit, or may not transmit, the unique information ofthe wireless power transmitter to the wireless power receiver. In thiscase, the wireless power receiver determines whether the uniqueinformation of the wireless power transmitter is received from thewireless power transmitter. If the wireless power transmitter does nottransmit its unique information to the wireless power receiver, thewireless power receiver transmits default unique information to thewireless power transmitter. The default unit information may include,for example, the BLE device address information.

The wireless power transmitter may determine whether the swap occursbased on the unique information of the wireless power receiver. Forexample, if the wireless power receiver transmits the unique informationof the wireless power receiver by using in-band communication and thewireless power transmitter receives the unique information of thewireless power receiver, the wireless power transmitter determines thatthe swap does not occur. Otherwise, if the wireless power receiver doesnot transmit the unique information of the wireless power receiver byusing in-band communication within a specific given time or if thewireless power transmitter fails in reception of the unique informationof the wireless power receiver despite the fact that the uniqueinformation of the wireless power receiver is transmitted, the wirelesspower transmitter may determine that the swap occurs.

In another aspect, the swap detection at the request of the wirelesspower transmitter may include a step in which the wireless powertransmitter uses out-band communication to request the wireless powerreceiver to provide bit pattern information of the wireless powerreceiver and a step in which the wireless power receiver uses in-bandcommunication (ASK) to transmit the bit pattern information to thewireless power transmitter in response to the request. The presentembodiment may further include a step in which the wireless powerreceiver changes impedance at the request of the wireless powertransmitter, and a step in which the wireless power transmitter detectsthe changed impedance to confirm that it is still in a magnetic couplingstate with respect to the same wireless power receiver (or it is placedabove the wireless power transmitter). If swapping occurs and thus thewireless power transmitter is in a magnetic coupling state with respectto another wireless power receiver (or if another wireless powerreceiver is placed above the wireless power transmitter), swapping canbe detected since the wireless power receiver does not respond to therequest of the wireless power transmitter. In this case, uniqueinformation of the wireless power transmitter or receiver is notparticularly required. Since there may be problem in quality of in-bandcommunication when high-power transmission is performed, in order toimprove swap detection performance, a method of transferring simple bitpattern information as shown in the present embodiment may be morepreferable than a packet type.

If the swap is detected, the wireless power transmitter and the wirelesspower receiver may return to the selection phase.

The wireless power transmitter according to the embodiment of FIG. 25and FIG. 26 corresponds to the wireless power transmitter, wirelesspower transmitting unit, or power transmitting portion of FIG. 1 to FIG.11. Therefore, an operation of the wireless power transmitter in thepresent embodiment is implemented by combining one or two or more ofcomponents of the wireless power transmitter of FIG. 1 to FIG. 11.

In addition, the wireless power receiver according to the embodiment ofFIG. 25 and FIG. 26 corresponds to the wireless power receiver, wirelesspower receiving unit, or wireless receiving portion of FIG. 1 to FIG.11. Therefore, an operation of the wireless power receiver for each stepin the present embodiment is implemented by combining one or two or moreof components of the wireless power receiver of FIG. 1 to FIG. 11.

According to embodiments of the present specification, initial phasesare performed by in-band communication, and preliminary informationrelated to out-band communication is exchanged by in-band communicationin the negotiation phase or the handover phase. When conforming to thismethod, a time required until the handover to out-band is complete isconfirmed through experiments. In this experiment, Bluetoothcommunication (BLE) is used as out-band communication. A time durationfrom the selection phase until a handover to Bluetooth is complete (oruntil a Bluetooth connection establishment is complete) may be dividedinto: i) an in-band communication duration; and ii) a Bluetoothconnection establishment duration.

First, a required time of the in-band communication duration iscalculated as follows with reference to FIG. 27.

FIG. 27 is a flowchart illustrating a procedure of performing a handoverto Bluetooth and a simulation of a required time according to anembodiment.

Referring to FIG. 27, an in-band communication duration includes signalstrength packet transmission (ASK communication), identification packettransmission (ASK communication), configuration packet transmission (ASKcommunication), ND transmission (FSK communication), OOB linkinformation transmission (ASK communication), and ACK transmission (FSKcommunication). An experiment result confirms that it takes about 278 msto 352 ms. A simulation condition is that an operating frequency is 100kHz, a polarity of FSK is positive, a depth is 1 (used as −78 ns), and 6bytes (44 ms is required) is used as out-band link information in ASKcommunication for the out-band link.

Next, a Bluetooth connection establishment duration includes threesub-durations of advertising, CONNECTION_IND message transmission, andlink connection setup. A total required time of the Bluetooth connectionestablishment duration may be acquired by calculating and adding aprocessing time of each of the three sub-durations. Therefore,hereinafter, a required time of the Bluetooth connection establishmentduration is calculated with reference to FIG. 28 to FIG. 32.

FIG. 28 is a flowchart illustrating an advertising operation timing inBluetooth communication.

Referring to FIG. 28, an advertising duration ‘advInterval’ may be 20ms, and an advertising delay ‘advDely’ may be 0 ms to 10 ms according toa pseudo-random value. The ADV_IND packet as shown in FIG. 29 isadvertised by a timing based on FIG. 28. The ADV_IND packet consists of47 bytes (payload 37 bytes+overhead 10 bytes), which is equivalent to376 bits. Herein, the payload includes an AdvA field indicating a BLEdevice address (MAC address) of a wireless power receiver, and anAdvData field including UUID indicating a wireless charging service. TheADV_IND packet of 47 bytes is advertised according to the timing of FIG.28, and a required time is calculated to be about 0.4 ms.

FIG. 30 is a flowchart illustrating a transmitting timing of aCONNECTION_IND message in Bluetooth communication.

Referring to FIG. 30, scan window and scan interval parameters forBluetooth communication of a wireless power transmitter are set to thesame value, so that a Bluetooth link layer of the wireless powertransmitter can continuously scan primary advertising channels.

An inter frame space (IFS) time T_IFS is 150 us, and a CONNECT_INDmessage is 352 bits, i.e., 44 bytes ((preamble(1B)+accessaddress(4B)+header(2B)+payload(34B)+CRC(3B)) as shown in FIG. 31.Therefore, a time required for transmission of the CONNECT_IND messageis about 0.4 ms. For reference, as shown in FIG. 31, the CONNECT_INDmessage includes an InitA field indicating a Bluetooth device address ofthe wireless power transmitter, an AdvA field indicating a Bluetoothdevice address of a wireless power receiver, and an LLData fieldincluding a parameter related to a connection.

FIG. 32 is a flowchart illustrating a timing of a link connection setupin Bluetooth communication.

Referring to FIG. 32, a transmission window delay ‘transmitWindowDelay’for a CONNECT_IND message is 1.25 ms, a transmission window offset‘transmitWindowOffset’ is a multiple of 1.25 ms in the range from 0 msto connInterval, a transmission window size ‘transmitWindowSize’ is amultiple of 1.25 ms in the range from 1.25 ms to a smaller value between10 ms and (connInterval-1.25 ms), and connecInterval is defined as amultiple of 1.25 ms in the range from 7.5 ms to 4.0 s. Therefore, a timerequired for a link connection setup is less than 61 ms+1.25 ms+0 ms+10ms=72.25 ms.

A time required until the handover to Bluetooth is complete (or until aBluetooth connection establishment is complete) is a sum of: i) arequired time T_IB of an in-band communication duration; and ii) arequired time T_BLE_Setuptime of a Bluetooth connection establishmentduration. Therefore, according to an experiment result of FIG. 27 toFIG. 32, it is confirmed that T_IB+T_BLE_Setuptime=425 ms (=352 ms+73ms).

In a wireless power transmitting method and device or receiving deviceand method according to embodiments of this specification, because allcomponents or steps are not essential, the wireless power transmittingdevice and method or receiving device and method may be performed byincluding some or all of the above-described components or steps.Further, embodiments of the wireless power transmitting device andmethod or receiving device and method may be performed in combination.Further, it is not necessary that the above components or steps shouldbe performed in the described order, and a step described later may beperformed prior to a step described earlier.

The foregoing description is merely illustrative of the technical ideaof this specification, and various changes and modifications may be madeby those skilled in the art without departing from the essentialcharacteristics of this specification. Therefore, the foregoingembodiments of this specification can be implemented separately or incombination.

Therefore, the embodiments disclosed in this specification are intendedto illustrate rather than to limit the scope of this specification, andthe scope of the technical idea of this specification is not limited bythese embodiments. The scope of protection of this specification shouldbe construed according to the following claims, and all technical ideaswithin the scope of equivalents to claims should be construed as fallingwithin the scope of this specification.

What is claimed is:
 1. A wireless power receiver configured to supportheterogeneous communication, the wireless power receiver comprising: apower pick-up unit configured to (i) receive wireless power from awireless power transmitter through magnetic coupling with the wirelesspower transmitter at an operating frequency and (ii) change analternating current (AC) signal generated by the wireless power into adirect current (DC) signal; and a communication/control unit configuredto receive the DC signal provided from the power pick-up unit andperform communication with the wireless power transmitter, wherein thecommunication/control unit is configured to perform at least one of (i)in-band communication using the operating frequency or (ii) out-bandcommunication using a frequency other than the operating frequency, andwherein the communication/control unit is further configured to receivein a negotiation phase, through the inband communication, a capabilitypacket comprising (i) information for potential power and (ii) anout-band flag informing whether the wireless power transmitter supportsthe out-band communication.
 2. The wireless power receiver of claim 1,wherein the communication/control unit is further configured to transmitinformation regarding handover to the out-band communication to thewireless power transmitter in the negotiation phase, based on thein-band communication.
 3. The wireless power receiver of claim 2,wherein the information regarding the handover to the out-bandcommunication comprises an out-band medium access control (MAC) addresspacket of the wireless power receiver.
 4. The wireless power receiver ofclaim 1, wherein the communication/control unit is further configured totransmit information regarding handover to the out-band communication tothe wireless power transmitter in a handover phase, based on the in-bandcommunication.
 5. The wireless power receiver of claim 4, wherein theinformation regarding the handover to the out-band communicationcomprises an out-band medium access control (MAC) address packet of thewireless power receiver.
 6. The wireless power receiver of claim 1,wherein handover to the out-band communication is initiated by thecommunication/control unit receiving a request signal which requests forinitiation of the handover to the out-band communication from thewireless power transmitter.
 7. The wireless power receiver of claim 6,wherein the request signal is a bit pattern of 8 bits informing thehandover to the out-band communication.
 8. The wireless power receiverof claim 1, wherein the communication/control unit is further configuredto: perform the out-band communication with the wireless powertransmitter in a power transfer phase based on completion of handover tothe out-band communication; and transmit unique information or bitpattern information for swap detection of the wireless power receiver tothe wireless power transmitter by using the in-band communication in thepower transfer phase.
 9. A wireless power transmitter configured tosupport heterogeneous communication, the wireless power transmittercomprising: a power conversion unit configured to transmit wirelesspower to a wireless power receiver through magnetic coupling with thewireless power receiver at an operating frequency; and acommunication/control unit configured to perform at least one of (i)in-band communication using the operating frequency or (ii) out-bandcommunication using a frequency other than the operating frequency,wherein the communication/control unit is further configured to transmitin a negotiation phase, through the inband communication, a capabilitypacket comprising (i) information for potential power and (ii) anout-band flag informing whether the wireless power transmitter supportsout-band communication to the wireless power receiver.
 10. The wirelesspower transmitter of claim 9, wherein the communication/control unit isfurther configured to receive information regarding handover to theout-band communication from the wireless power receiver in thenegotiation phase, based on the in-band communication.
 11. The wirelesspower transmitter of claim 10, wherein the information regarding thehandover to the out-band communication comprises an out-band mediumaccess control (MAC) address packet of the wireless power receiver. 12.The wireless power transmitter of claim 9, wherein thecommunication/control unit is further configured to receive informationregarding handover to the out-band communication from the wireless powerreceiver in a handover phase, based on the in-band communication. 13.The wireless power transmitter of claim 12, wherein the informationregarding the handover to the out-band communication comprises anout-band medium access control (MAC) address packet of the wirelesspower receiver.
 14. The wireless power transmitter of claim 9, whereinhandover to the out-band communication is initiated by thecommunication/control unit transmitting a request signal which requestsfor initiation of the handover to the out-band communication to thewireless power receiver.
 15. The wireless power transmitter of claim 14,wherein the request signal is a bit pattern of 8 bits informing thehandover to the out-band communication.
 16. The wireless powertransmitter of claim 9, wherein the communication/control unit isfurther configured to: perform the out-band communication with thewireless power receiver in a power transfer phase based on completion ofhandover to the out-band communication; and receive unique informationor bit pattern information for swap detection of the wireless powerreceiver from the wireless power receiver by using the in-bandcommunication in the power transfer phase.
 17. A method of performingheterogeneous communication by a wireless power receiver configured toreceive wireless power from a wireless power transmitter throughmagnetic coupling with the wireless power transmitter at an operatingfrequency, the method comprising: receiving in a negotiation phase, fromthe wireless power transmitter through in-band communication using theoperating frequency, a capability packet comprising an out-band flaginforming whether the wireless power transmitter supports out-bandcommunication using a frequency other than the operating frequency;receiving, from the wireless power transmitter, a request signal whichrequests for a handover to out-band; performing the handover toout-band; receiving the wireless power in a power transfer phase; andtransmitting, to the wireless power transmitter by using the in-bandcommunication in the power transfer phase, identification informationfor swap detection of the wireless power receiver.